There is a vast area of cold regions distributed in China. The problems that freezing-thawing damage will seriously threaten the stability of rock engineering need to be solved，which involve the thermo-hydro- mechanical(THM) coupling problem at a low temperature. Considering the migration of water and phase transition，the distributions of stress field and stress intensity factor near the fracture are analyzed by using the theories of fracture mechanics and elastoplastic mechanics. Considering the effect of temperature on freezing ratio，the frost load is simulated by method of equivalent coefficient of thermal expansion. Finally，the model for freezing fracture is established with FISH program to simulate the stress field near the fracture；and comparisons between numerical and analytical results are made.

A new cutting method named quasi-parallel cutting method is proposed according to the rock blasting theory；and it helps to achieve the goal of rapid drivage for rock roadway by drilling and blasting and to overcome the deficiencies in parallel cutting and inclined-hole cutting. Quasi-parallel cutting method is a break through to the traditional cut blasting design. Main cutting holes(quasi-parallel holes) are slightly inclined；their distances at the bottom are long；and sub-cutting holes are perpendicular to the free face. Compared with current cutting methods，it has the following advantages：(1) It avoids the phenomenon of drilling holes crossing each other because of long distance at the bottom of quasi-parallel holes. (2) Slicing and stage blasting method is used at a reasonable interval time. (3) Straight sub-holes in the center and the symmetrical quasi-parallel holes cooperate with each other；it is a successful combination of parallel cutting method and inclined-hole cutting method. (4) The cutting form is very simple and easy to operate. (5) It can get large cavity with high efficiency and low-cost. Based on the quasi-static theory of blasting gas and the limit equilibrium theory of rock mechanics，the generation process of cavity has been analyzed. For the purpose of optimizing the quasi-parallel cutting parameters，a series of field tests are carried out；technical parameters of cutting holes including layout，depth，angle of inclination，spacing，charge and the interval time of short-delay blasting are obtained under different blasting conditions. Angle of quasi-parallel hole is determined by measuring length during construction，which can meet its accurate requirements. The test results show that the better blasting effect and obvious technical and economic benefits in coal rock drivage can be acquired by means of the quasi-parallel cutting method.

Geographic orientation of geostress is an important basic parameter for reasonable well layout，hydraulic fracturing design，optimization of directional orientation of complex structural well and determination of safe drilling fluid density window. According to the problems that laboratory geostress testing methods can not determine the geographic orientation of horizontal geostress for nondirectional cores，the geographic orientation of cores is calibrated by using viscous remanent magnetization component；the acoustic emission Kaiser test under confining pressures for calibrated cores is carried out so as to determine the magnitude and relative orientation of horizontal geostress. Eventually，the geographic orientations of the maximum and minor principal geostresses are determined. This method solves the problem that the geographic orientation of geostresses can not be determined by using Kaiser test and improves the testing methods of geostress in deep formation. Meanwhile，it provides basic data for drilling engineering and optimization of oilfield stimulation.

The rheological deformation of surrounding soft rock of roadway in deep mine can be caused by perturbation load. In order to establish the constitutive relation of roadway surrounding rock，the testing machine for rock rheological perturbation effect should be developed to conduct experiments. The testing machine is able to apply long-term constant axial pressure and confining pressure and perturbation load，and to test the perturbation load and rock deformation. The developed RRTS–II testing machine for rock rheological perturbation effect，whose axial pressure adopted by gravity loading，is suitable for long-term rheological test. The axial loading is achieved by gear and hydraulic structures；the pressure can reach 100 MPa，which is up to 60–100 times than the gravity loading. The perturbation load applied by impact and blast can be measured by blasting vibration recorder，whose measurement accuracy is 0.015 mm/s. The confining pressure applied by triaxial cell，which is achieved by high pressure gas energy storing device，can reach 10 MPa. The testing machine is equipped with load，displacement，strain and vibration test systems and corresponding data processing software. It is suitable for uniaxial and triaxial compression tests under low confining pressure with perturbation load. Test results show that the testing machine has reasonable structure，stable performance and high precision.

Based on the conditions of #16 coal seam of Lutian coal mine，a new mining method adopting the roadway layout with L-shape is proposed and carried out successfully. The caving characteristics of the top coal and roof，the working resistances of the powered support，the subsidence and collapse rules of the ground surface，the backfill and the roller compaction technology and the other aspects of the fully-mechanized top coal caving for the shallow-buried thick coal seam are studied by field observation. The evolution of the roof rupture and collapse is analyzed. The mechanical model of arch and step voussoir beam combination is established. The movement law of overlying strata and the crushing mechanism of the top coal are revealed；and the powered support resistance formula for controlling roof stability is put forward. The study results show as follows：(1) The mining method of L-shaped working face is a kind of method with high efficiency，safety and high recovery；it is a meaningful reference to outcrop mining or transition from open-pit to underground mining. (2) It is feasible in technology to use fully-mechanized sublevel caving mining for the shallow-buried thick coal seam under the appropriate mining conditions. (3) The periodic weighting step distance increases with the increasing thickness of overlying strata. (4) The periodic weighting is obvious in the middle of working face. (5) The subsidence and collapse of the ground surface can be divided into 4 stages；the backfills and the roller compaction should be divided into 2 stages. (6) In order to enhance the stabilities of the roof and the coal wall，it is essential to increase the initial supporting force of powered support. The results can be referred for further studies in similar conditions.

According to the features of underwater shield tunnel with large cross-section，an integrated test method is proposed for prototype segmental lining structure，including joint structure and whole ring lining structure. The “Multifunction Shield Tunnel Structure Loading Test System”has been developed according to the test method. The system not only can perform the prototype test of segmental lining structure，but also can test the mechanics of joints. Then the test method and test system are applied to prototype tests for Nanjing Changjiang tunnel and Guangzhou Shiziyang tunnel. Meanwhile，joint bending stiffness and shear stiffness are both obtained successfully through a series of tests；and a part of results obtained by prototype tests is compared with numerical results to verify the accuracy and reliability of the test method and test system，so as to provide reliable test means for research，design and construction of underwater shield tunnel projects.

The bedded rocks have anisotropic and elastoplastic coupling mechanical properties. The elastic parameters of anisotropic rocks are the functions of plastic strain and loading angle. On this basis，triaxial cyclic loading and unloading tests of argillite with obviously bedded structures are designed and completed. The study results show that with the increase in plastic strain, the apparent elastic modulus decays exponentially，whereas the Poisson?s ratio increases. According to this phenomenon，two empirical functions are proposed to describe the relationships of apparent elastic modulus and apparent Poisson?s ratio vs. axial plastic strain and loading angle of rock specimens；and the values of related parameters are also obtained. The curved surface of apparent elastic modulus in the three-dimensional space changing with loading angle and plastic strain is drawn. The anisotropic degree of elastic modulus decreases with the development of plastic strain.

According to the difficulties and shortcomings of real-time microseismic monitoring during tunnel boring machine(TBM) tunneling with overburden of over 2 000 m-thick hard and brittle rock mass，the traditional microseismic monitoring technology，used in the mines，is optimized and improved；and the new microseismic monitoring technology is utilized during the TBM tunneling in the diversion tunnel #3 of Jinping II hydropower station. The monitoring results show as follows：(1) The ambient noise is much and complex，but the main characteristic is clear during TBM tunneling；and it can be filtered through the proposed filtering method effectively. (2) There is an obvious relationship that microseismic activity increases with the increase in TBM tunneling rate between microseismic activity of surrounding rock mass and the TBM tunneling rate，vice versa. Microseismic activity is very weak during the period of TBM maintenance，but it becomes most active when TBM working lasts for 4–6 hours after TBM maintenance. (3) Before some rockburst occurred，distribution of microseismic events and energy release gradually convert from discrete to relatively concentrative in spatial domain，the number of microseismic events and the radiated energy increase rapidly in temporal domain；and apparent volume of surrounding rock mass has a sudden increasing trend；energy index has a sudden drop trend in the same time. (4) When microseismic monitoring is carried out during TBM tunneling covered with thickly hard and brittle rock mass，effective microseismic information can be acquired；the evolution characteristic and law of microseismic activity can be found and known；and more accurate early-warning information of rockburst can be provided. Therefore，it is possible and feasible to forecast the occurrence of rockburst by microseismic monitoring.

Based on the technical problems of the grouting fluid flowing along the steep crack faces and the poor reinforcement effects in the grouting reinforcement projects for strong unloading，loose and damaged rock mass induced by the strong earthquake，the SJP–1 aging strengthening cement-chemical grout is developed. The effect of the high-molecular compound additive on the formation rate of calcium silicate hydrate is discussed；and a new theory of solvability film of cement-chemical grout is proposed. The experimental results indicate that the pumpability period of the new cement-chemical grout is 30–90 minutes，initial setting time is 90–210 minutes，final setting time is 130–290 minutes，and the long-term strength of SJP–1 cement-chemical grout is about 10%–20% higher than that of the ordinary cement grout. SJP–1 cement-chemical grout can solve the shortcomings of the higher early strength and the lower long-term strength for the quick setting cement grout，and can reduce the construction cost. Finally，the SJP–1 cement-chemical grout is used successfully in the grouting reinforcement projects for damaged rock masses of Jinping I hydropower station and Wenchuan earthquake disaster area.

The studies of dissolution characteristics of salt rock under high temperature and triaxial pressure are the basis of quickly and safely constructing the underground storage and controlling its shape. The test method for the dissolution characteristics of salt rock under high temperature and triaxial compression is put forward. The formula for calculating the dissolving rate of salt rock is deduced and the error analysis is carried out. Based on this method，the triaxial testing machine with high temperature for dissolution characteristics of salt rock is successfully developed. The highest test temperature of the machine is 95 ℃；the maximum axial force is 400 kN and the maximum confining pressure is 30 MPa. The standard salt rock sample with 50 mm or 100 mm in diameter or rectangular sample with size of 50 mm×50 mm×100 mm can be tested by using this self-developed testing machine. The key technical problems of the water passing through the salt rock test sample and the questions of the seal，keeping pressure and corrosion of machine under high temperature are solved. The testing machine is used to test the sample obtained from a rock salt gas storage. The results show that the testing process is stable；the testing data has high precision and the testing system is reliable. The testing machine can be used to study the dissolution characteristics of salt rock for the underground project such as solution mining of salt rock and using the underground salt cave to store the petroleum，gas or radioactive nuclear waste. The results provide the basic parameters for quickly and safely constructing salt cave and controlling its shape.

The stability criterion for underground caverns based on the unbalanced force and the minimum plastic complementary energy is introduced into the software fast Lagrangian analysis of continua in three dimensions (FLAC3D)，and its equivalent form is deduced. The rationality of using the maximum unbalanced force and the plasticity distribution to determine the stability and using the unbalanced force distribution and adjustment process to indicate the destruction location and evolution path of storage group is demonstrated. The layout of dense storage group is optimized from two aspects of the reasonable space between two caverns and the layout pattern，respectively. The results show that distance 1.5 times of cavern diameter is safe and economic between two caverns；and equilateral triangle layout is the optimal plane layout pattern. Two kinds of destruction sources in the storage group are compared. The results show that the influence of sudden pressure loss starting from internal caverns is more significant and cause more serious damage than that from the outlying caverns. The stability of single internal cavern with sudden pressure loss is analyzed by using equilateral triangle layout. Considering the long-term strength reduction of salt rock，the stability of the same model is carried out. The results are applied to the chain destruction analysis later as an indicator of local failure. The chain destruction process is studied by numerical simulation；and the results show that the sudden pressure loss in single cavern doesn′t tend to cause chain destruction of storage group.

Using the self-developed charge-induced instrument，the experimental system for collecting the charge-induced signal in the process of coal deformation and fracture is set up. The law of charge induction of coal in the same mine during the coal deformation and fracture process is studied under different loading rates in laboratory. The experimental results show that the charge-induced signal is generated during the deformation and fracture process of coal；and the charge-induced signal is the instantaneous pulse. The charge-induced signal strength is the most powerful before the peak stress of coal；and the signal strength is more powerful when coal damages. The charge-induced signals on all surfaces are asynchronous，and their magnitudes are varied. The charge-induced signal strength is more powerful at the larger fracture surface. The greater the loading rate is，the stronger the charge-induced signal strength is. Under sudden loading and unloading，there would generate charge-induced signal with low strength. The main reasons for charge generation in the process of coal deformation and fracture are friction and crack tip charge separation because of micro-rupture. The results suggest that the charge-induced signal is closely related to the deformation and fracture of coal；the status of coal deformation and fracture may be determined by the charge-induced signal. The charge induction method is applicable to studying the exploration of the rock deformation and failure process and predicting catastrophic dynamic phenomena.

The theory and method are studied for anisotropic strength criteria of jointed rock mass，based on Mohr-Coulomb and Rankine criteria by introducing the persistence ratio and strength parameters of rock mass obtained from network simulation. The above theory and method are adopted to establish anisotropic strength criterion and make dynamic analysis for deep sliding surface of dam-rock foundation system. The analytical results show that the failure plane by anisotropic strength criterion cannot coincide with the maximum shear stress plane. It can improve the shortcoming of Mohr-Coulomb criterion for overestimating the material tensile strength of rock mass by combining Rankine and Mohr-Coulomb criteria. The strength criterion can simulate the failure characteristics of jointed rock mass reflected by relationship between resistance and response.

The effect of confining pressure on evolution law of hysteresis loop of sandstone under cyclic loading is investigated by using MTS815 rock mechanics testing system. Test results are shown as follows：(1) The hysteresis loop can be divided into two parts to perform quadratic fitting. In cyclic loading section，with the increase in cycle，fitting parameters A and B increase with the increase in confining pressure；while the fitting parameter C decreases with the increase in confining pressure. The opening of fitting curve increases gradually and tends to be stable；the greater the confining pressure is，the less the time it need to be stable is. In cyclic unloading section，with the increase in cycle，fitting parameter A decreases with increase in confining pressure；fitting parameters B and C decrease with the increase in confining pressure. The openings of fitting curves increase gradually and tend to be stable；the greater the confining pressure is，the larger the opening of fitting curve is. (2) Hysteresis loop area of sandstone increases with the increase in confining pressure，which means that with the increase in confining pressure，the dissipation energy of specimen in each cycle increases and the crack propagation energy needed also increases. (3) The relationship between the axial dissipation energy and cycle accords with the power of negative exponent function under cyclic loading；and the feature of the curve is that with the increase in cycle，the axial dissipation energy per unit volume attenuates quickly and tends to be stable gradually.

According to the five most common failure criteria considering the influence of intermediate principal stress，the corresponding internal friction angle expressions considering the influence of intermediate principal stress are deduced. The relationships between internal friction angle and intermediate principal stress coefficient under true triaxial stress are established；and it is a new perspective of discussing the influence law of intermediate principal stress. Based on the comparison with the true triaxial test results of gravelly soil，dense sand and loess，the reflection degree of the intermediate principal stress considered in each criterion is studied and the applicability is discussed with the quantitative analysis of standard deviation. The study results show that the five criteria reflect intermediate principal stress to different extents. The fitting effect of Drucker-Prager criterion is the worst and that of modified Lade-Duncan criterion is the best，while the fitting effects of the other three failure criteria are almost the same. Different criteria should be chosen for different materials.

When a tunnel is constructed by blasting，the stability of surrounding rock near tunnel face is important for safety of builders and tunnel itself. It is testified that the blasting vibration rule obtained from area remote blasting source is not suitable for the area near tunnel blasting source. So it is necessary to test blasting vibration of the surrounding rock near tunnel blasting source and to study the blasting vibration rule. Based on Qipanshan tunnel of Guiyang—Guangzhou railway，the tailor-made blasting vibration sensors are disposed in the arch crown surrounding rock within the range of 5 m to test the blasting vibration velocity. Taking advantage of middle drift excavation，the tailor-made blasting vibration sensors are disposed in upper and side surrounding rocks within the range of 2 m to test blasting vibration velocity. The blasting vibration rules of arch crown and upper and side surrounding rocks behind tunnel face are studied. The study results can provide references for tunnel blasting construction.

According to the problem of leakage bypassing the dam in Wudongde hydropower station and the deficiency of the two-dimensional and quasi-three-dimensional steady flow models，on the basis of the sufficient analysis of geology and hydrogeology characteristics of dam site，a hydrogeology conceptual model is generated；a three-dimensional transient flow numerical simulation model is established，which is solved by the finite difference method and the preconditioned conjugate gradient method. Based on the simulation of the three-dimensional seepage fields under the three working conditions including natural state，normal water storage with impervious curtain and normal water storage without impervious curtain，according to the principle of water balance，the seepage quantities of various schemes in dry and wet season are calculated. The results show that the seepage quantity bypassing the dam on the right bank is about 5.7 times that of the left bank；compared with the system without anti-seepage treatment，the total seepage quantity can reduce by 72.98% after anti-seepage treatment；the seepage quantities bypassing right and left dam abutments and the dam foundation in wet season are less than those in dry season. It is shown that the convergence speed of the model is fast；and the stability of the model is good.

The scale effect of density on the mechanical properties of coarse-grained dam materials is ignored in previous studies. On this basis，four scale methods are used to obtain the maximum dry density in laboratory according to the original average design gradation curve of rockfill in Shuangjiangkou earth-rockfill dam. Based on the design generatrix of the coarse-grained dam materials gradation—Talbot curve and fractal geometry theory，the mechanism of scale effect of density for coarse-grained dam materials is interpreted，which selects the Talbot formula index and the factor reflecting the particle shape and roughness as the fractal indices. The basis of quantitatively evaluating the effect of gradation on density is provided；and the shortcomings of fuzzy evaluation only using the non-uniformity coefficient and curvature coefficient is overcome. Combined the mixed scale method，the numerical tests on the maximum dry density is carried out by using the particle flow code in two dimensions(PFC2D)；the law of scale effect on the relative density and porosity of coarse-grained materials is studied；and the microscopic mechanism causing the difference is analyzed.

The dominant occurrence and geometric information of rock mass discontinuities are the important indices to evaluate the development of rock mass discontinuities. Discontinuity information of high and steep slope or unstable slope is unavailable using the traditional compass measurement，therefore the geometric information of rock mass discontinuities cannot be obtained accurately. The technology of three-dimensional(3D) laser measurement can help to obtain 3D point cloud data with high precision of rock mass discontinuities at long distance location；then the geometric information of rock discontinuities can be obtained and the automatic fuzzy clustering statistical analysis is realized. With triangular mesh reconstruction of 3D laser point cloud data，normal vector and occurrence of plane equation of reconstructed triangular mesh are calculated；the occurrence of rock discontinuities is classified by fuzzy C-mean clustering method and the clustering classification results of discontinuity are shown with different colors. The automatic statistical analysis software FSS is programmed with interactive data language(IDL) based on mass laser point cloud data of rock mass discontinuity. The method is adopted to statistically analyze the dominant occurrence of naked rock mass slope discontinuity in Qiaoxin Town of Huairou County；and the results show that the proposed method has the advantages of rapidness and long-distance measurement with reliable and reasonable results of clustering classification.

The drained triaxial shear creep tests for Zhanjiang strong structured clay under different confining pressures by GDS triaxial testing system are performed. The relationships of axial strain and volumetric strain with stress and time are obtained. The effect of soil structural property on its creep behavior is analyzed；and the corresponding creep model is established. The results show that the evolution characteristics of creep deformation of Zhanjiang clay are restricted by its poorly structural property；and its sensitivity is related to the structural property of soil. The creep deformation and deformation rate of Zhanjiang clay are small in the range of low deviatoric stress；when the deviatoric stress exceeds a critical value，the soil mass failure occurs in a short time. The overall behavior of volumetric strain of Zhanjiang clay in the process of drained triaxial shear creep presents shear contraction，while a certain shear contraction and shear dilation alternately appear during the creep time under the condition of ?3＜?k，i.e. there exists rebound phenomenon；and it presents shear contraction when ?3≥?k. The strength attenuation induced by creep mainly results in cohesion reduction，and   77.63%. It is found that the six-element extended Burgers model could effectively describe the three deformation stages of the instantaneous elastic strain，attenuation creep and stable creep for Zhanjiang clay. In actual project，the soil structural property should be clearly understood；the favorable factors of structural property of soil could be used in low stress level；but the designed load is forbidden to exceed the structural yield stress.

Based on the experimental results obtained from a series of high precision triaxial isotropic loading and unloading tests and plane strain compression tests along different stress paths on Toyoura sand，a modified plastic work volumetric hardening function is proposed under plane strain conditions. The modified plastic work shear hardening function is presented within the framework of double hardening. The modified plastic work shear-volumetric double hardening function is established，which is independent of stress path for Toyoura sand. On the basis of proposed modified plastic work double hardening function，an incremental type shear-volumetric double hardening elastoplastic stiffness matrix is deduced；then the constitutive model considering multiple influential factors on deformation and strength is established for Toyoura sand. The comparisons between the numerical and the experimental results show that the proposed double hardening constitutive model can reasonably simulate the deformation and strength characteristics of sand.

Both the pressure plate and vapor transfer technique are used to measure the soil-water characteristic curves(SWCCs) of bentonite-sand mixtures for understanding the effects of initial saturated condition，sand mix ratio and dry density on water-holding capacity in drying process. With respect to the bentonite-sand mixtures saturated under confined condition，it is found that the water-holding capacity decreases with the increase in sand mix ratio and dry density. While for the bentonite-sand mixtures saturated under free condition，the water-holding capacity is found to be constant with different dry densities. By introducing the effective clay density and the effective water content，the measured SWCCs of bentonite-sand mixtures are modified to illustrate the major factors controlling the water-holding capacity of mixtures under different saturated conditions. It is found that the water-holding capacity of mixtures saturated under confined condition is mainly controlled by effective clay density；while that saturated under free condition is mainly controlled by sand mix ratio. The empirical equations of modified SWCCs of GMZ001 bentonite-sand mixtures with various sand mix ratios are fitted based on test data，and they can be used to estimate the unsaturated water content of the mixed backfill/buffer material in high-level waste disposal project.

The traditional model based on triaxial cyclic loading test could not reflect the phenomenon of initial principal stress axis deviation of soil element under gravity stress. The cyclic loading test data for building the constitutive model considering the influence of deviation angle of principal stress axis can be obtained by the dynamic hollow cylinder shear test. The equipment for making the soft clay hollow cylindrical sample is manufactured according to the physico-mechanical properties of the 4th layer of saturated soft clay in Shanghai. Under the constant deviation angle of principal stress axis，the cyclic loading waveform equation and the total stress loading equation which could control the static shear test are deduced. The undrained shear tests and dynamic tests of the 4th layer of saturated soft clay in Shanghai are carried out under different constant deviation angles of principal stress axis. After discussing the rules that the deviation angle of principal stress axis affects the cyclic accumulative strain and the undrained shear strength，the explicit model is put forward which could reflect the deviation angle of principal stress axis. The model parameters are of physical significance and are easy to be obtained. The explicit model is validated based on undrained cyclic test data. It will be more effective to calculate the long-term settlement of subgrade under traffic loading with the proposed explicit model.

To study the effect of particle shape on mechanical and deformation properties of sand，three kinds of sands with different particle shapes and similar materials that are glass beads are selected. A light microscope is employed to capture the particle digital images，which are then processed to obtain the geometric parameters of particles. Two shape parameters，sphericity and roundness，are defined and quantified using the plug-in JAVA language. A series of direct shear and centrifugal cone penetration tests(CPTs) are conducted to examine the relative effect of particle shapes on the shearing friction angle and pile tip resistance. The direct shear test results show that the critical friction angle reduces linearly with the increase in roundness and particle regularity，while the dilation angle increases with the increase in particle irregularity. A modified equation can be employed to describe the relative effect of particle shapes on the peak friction angle. The centrifugal tests indicate the CPTs can be highly relied upon in the case of predicting the pile tip resistance. The sand that has a more irregular shape，i.e. deviation from sphericity and more angular，can exert a higher pile tip resistance. Moreover，an iterative method is proposed to quantify the interaction of pile tip resistance，relative density，stress level and particle shape；and the predicted tip resistance derived from this method agrees well with the measured one.

Due to the high bearing capacity，high productivity of installation and non-pollution on site，such soil displacement screw(SDS) pile has been widely applied in many countries. But there is no successfully engineering application report in China yet. To study soil compaction effect，bearing characteristics，distribution of side friction resistance of SDS pile and the difference between SDS pile and cement flyash gravel(CFG) pile，two field tests are carried out in a site in Beijing. Test results show that the surface vertical displacement during construction is mainly completed from the beginning of auger drilling to the auger′s compaction part squeezing into the soil wholly；then the surface vertical displacement tends to stabilize. The soil compaction effect is mainly completed within 4 times the pile diameter；and the higher the soil compressibility is，the larger the soil compaction scope is. The ultimate bearing capacity of SDS pile can be increased by 30%–50% compared with CFG pile at the same settlement of the pile top.

Soil water content and dry density are important parameters in geotechnical engineering. Conventional measuring methods are time consuming，destructive，and automatic multipoint real-time monitoring is not achieved. On the basis of electromagnetic theory and time domain reflectometry(TDR) method，the effects of TDR sensor type，material and size on the accuracy of the measurement are systematically analyzed. A new TDR sensor with advantages of good integrity，reliable performance and low cost is designed for the disadvantages of existing commercial sensors. Then，the practicability of TDR sensor is tested and verified by specially designed large-scale model test. The results show that the new sensor can be used to measure in-situ soil gravimetric water content and dry density accurately and quickly. Furthermore，the long-term real-time monitoring of soil water content and dry density at different depths can also be implemented by it. The new sensor is an efficient tool in quality control during construction and safety monitoring in the service period of geotechnical engineering projects.

Taking advantages of laser photoelectricity measurement technique and position sensing detector(PSD) with high precision，the laser measurement system for measuring radial deformation of triaxial specimens is improved. Three aspects of improvement have been done as follows：(1) In order to avoid the deflection of vertical incident light，the square pressure chamber is adopted instead of the circular one. (2) Two PSDs are used to measure radial deformation in left and right sides of specimen instead of one PSD in original system，which couldn′t take into account the specimen eccentricity in triaxial shear tests. So the measuring precision would be enhanced. (3) A stepper motor of controlling transducer lift and down is used instead of common motor. It can ensure the transducer goes back to the same initial position. This system is used to measure standard specimen，standard specimen in the pressure chamber and standard specimen in the pressure chamber full of water. The function relationship between change in electrical signal and change in diameter is obtained. The consolidation tests on saturated sand containing clay are carried out. The comparison of measured and calculated results indicates that the volumetric changing results obtained by the improved triaxial measurement system are reliable. This system can be applied to study the problem of triaxial specimens，such as local deformation and end restraint；it also has great prospect to study deformation localization，formation of shear zone and volumetric changing measurement of unsaturated soils.