With the sharp increasing in the requirements for tunnel maintenance of urban metro，the structural defects of the metro shield tunnels，especially the water leakage，need be inspected fast and accurately. Using the computer vision to inspect the structural defects of shield tunnel is a thriving trend home and abroad during recent years. However，the traditional methods of image recognition on water leakage cannot meet the need in engineering practice. In this paper，a novel method employing the fully convolution network(FCN) based on the deep learning(DL) is proposed to improve the image recognition on water leakage in shield tunnel. The water leakage images are divided into six categories according to the lining surface of shield tunnel and some interference on image recognition. The recognition results，the error rates and the running time from FCN are compared with those from the traditional image recognition methods of Otsu algorithm(OA)，region growing algorithm(RGA) and watershed algorithm(WA). The results show that DL-based image recognition on water leakage effectively avoided the interference from the segment joints，bolt holes，cables，brackets etc.，and has excellent robustness in overcoming the defects shelter from cables.

In order to study the effect of the angle of flaws at the end surface on the dynamic properties of and crack propagation in rock，cylindrical marble specimens of 50 mm×50 mm were manufactured with flaws of different angles. A series of impact loading tests were carried out with a system of split Hopkinson pressure bar(SHPB) with the diameter of 50 mm. The crack propagation and dynamic failure processes were recorded real-timely by a high speed camera. The results show that the dynamic parameters of the marble including the dynamic compressive strength，peak strain and dynamic elastic modulus，decrease first and then increase with the increasing of angles of prefabricated flaw. The cracks initiate almost from or near the tip of flaw and the initiation cracks belong to type II or combined type I-II. The crack initiation angle shows an M-shaped tendency and the crack initiation stress shows a W-shaped tendency with the increase of the flaw angle. The splitting tensile failure is usually observed in the marble specimen intact or with flaw having angle of 90°. The combined tensile-shear failure occurred mainly in the specimen with flaw angle of 45° and the shear failure in specimens with flaw angles of 30° and 60°. The crack propagation characteristics on both sides of the critical angle are rather symmetric. The energy absorption ratio increases first and then decreases with the increasing of the flaw angle. When the end flaw has an appropriate angle to the loading surface，the energy absorption ratio is the largest，indicating that the efficiency of rock breaking can be improved effectively by setting an appropriate flaw angle at the end surface.

Based on the fact that rock fractures are usually three-dimensional，the dimensionless stress intensity factors(i.e. YI and YII) of mode I and mode II and the dimensionless T-stress of the single edge notched deep beam(SENDB) specimen were calibrated using 3D numerical models，and compared with the results obtained with 2D numerical models from a reference. The 2D models usually provide the low values for SIFs and T* than the 3D models. Accordingly，the fracture toughness calculated with a 2D model was lower than the real fracture toughness value of rock，which may have an unfavorable effect in the design of fracturing-related rock engineering. The SENDB specimens made of sandstone were tested in a full range of mixed modes from pure mode I to pure mode II. The micro-crack zones(MFZ) were theoretically estimated based on the criterion of generalized maximum tangential stress (GMTS). Under the mode-I dominated loadings，the maximum MFZ was found in the middle of the specimen and the minimum MFZ on the sample surface. While for the mode-II dominated fractures，the size of the MFZ on sample surface is much larger than that in the middle of the sample. The critical radius of the MFZ for mode I fracture was much smaller than that for mode II fracture， indicating that the critical radius r0 of the MFZ in the crack propagation direction was not an invariant. It is obvious that the hypothesis of a constant r0 adopted by the GMTS criteria is questionable.

The bearing capacity，mechanical characteristics and damage mode of the special-shaped shield lining should be explored before application because of its special cross section. A 1∶1‘standing’prototype loading method for special-shaped segmental lining was suggested，and a‘standing’reconfigurable loading and data acquisition platform was developed with a hydraulic control system based on the closed-loop control theory of PLC. The internal force and deformation characteristics of the special-shaped shield lining structure under dead weight and overburden condition were analyzed respectively. The substantial influence of the structural self-weight on the internal force and deformation of the segmental lining under shallow overburden conditions was discovered. The limit burying depth of the lining structure was determined to be 18.5 m，and the analysis of the distribution of the cracks on the inner and outer surfaces of the segmental lining revealed the phenomenon of bending moment transfer.

Acoustic emission method(AE) is widely used in in-situ stress measurement. The cyclic loading method can be employed when the Kaiser effect is less pronounced in one cycle uniaxial compression test with AE monitoring. Usually，the peak stress of each cyclic loading is greater than the maximum stress that the rock ever experienced in the earth?s crust. To study the effect of the high stress on Kaiser effect of rock，cyclic loading test on marble specimens from the vertical drilling hole of Tonglushan mine was carried out. The take-off points in different loading cycles were determined according to the characteristics of AE curve and the results of in-situ stress measured with the methods of deformation rate analysis(DRA) and hydraulic fracturing. The results show that the high stress reduces the energy of AE events corresponding to ，diminishes the Kaiser effect in subsequent loading cycles and changes the magnitude of memorized stress in the rock at the same time. The repeated cyclic loading leads the destruction of rock?s internal microstructure，and the resulted AE obscures the take-off points. Besides，the high stress may replace and becomes the new stress memorized in the rock due to the differences of rock. In view of this，the peak loading stress of first cycle should not exceed ，and must make the specimen to enter the linear elastic stage. The reasonable range of the peak loading stress of first cycle is 6% to 28% of rock?s ultimate strength. In addition，the reasonable loading mode when AE and DRA method combined to measure geostress was given in the paper.

Three-point bending test on sandstone with different initial crack-depth ratios was carried out under different freezing-thawing cycles. The variation of the three-dimensional shape of the failure surface of specimens under the cyclic freezing-thawing was analyzed，and the relationships between the roughness coefficient and the initial load of fracture，peak load，fracture toughness and fracture energy were explored. The results show that the cyclic freezing-thawing reduces the values of initial load of fracture，peak load，fracture toughness and fracture energy of sandstone specimens to various extent and the extent of reduction is affected by the initial crack-depth ratio. The roughness coefficient of the failure surface of specimens increase with increasing freezing-thawing cycles and initial crack-depth ratio. When the initial crack-depth ratio is fixed，the relationship between the roughness coefficient and the freeze-thaw cycles is an exponential function. Under the effect of cyclic freezing-thawing，the damage factors of the peak load and the fracture toughness increase linearly with the increment of roughness coefficient.

Stress shadow effect and interference of fractures are of great significance in hydraulic fracturing engineering of oil and gas. Three types of interference factors were defined and the stress intensity factors(SIFs) of fractures in finite geological profile were calculated based on the weight function theory. The mechanisms of fracture interference were analysed. The SIFs obtained with the proposed method are more accurate than those with the traditional infinite fracture model. The effect of increasing breakdown pressure to enlarge stress shadow domain is limited. The disturbance factor has singularity when the breakdown pressure reaches its critical value. The stress shadow effect is apparently sensitive to the distance between fractures. The stress shadow effect is more obvious when it is located at half length of the hydraulic fractures in vertical wells. The stress shadow effect increases linearly with the increment of vertical geostress. The mechanism of variation of fracturing angle causing the fracture interference is very complicated which depends on the breakdown pressure induced stress and geostress. The interference between the closed fractures with negative SIFs is different from that between the conventional open fractures. The interference factor has the potential application prospect in evaluating the interference between the specially closed fractures. The alternating action of breakdown pressure and induced stress can result in the transition of competitive fracturing processes.

Tunnel construction is a complete system engineering. The characteristics of surrounding rock information and the monitored deformation，which is significant for future tunnel construction，have not been used effectively. Therefore，Gaussian process regression was proposed to establish the model of mapping between the natural properties and deformation of exposed rock mass based on the prior information of distribution of excavated surrounding rock. With the mapping model，the value of convergence deformation at excavating face can be predicted，and the stability of surrounding rock can be evaluated in real time. The interactive analysis on the stability of surrounding rock was carried out with the predicted deformation value as the pilot criterion. With the calculated results of multivariate heterogeneous information such as the interpreted data from the advance geological forecast，classification of field surrounding rock and so on，the mechanism of dynamic permit of construction and design change were established. In addition，the probability of whole deformation failure of the certain section with the same surrounding rock grade was evaluated using the GPR-MCS algorithm.

The presence of hard roof in underground coal mine is usually accompanied by the characteristics of high hardness，good integrity and huge thickness，which results in numerous problems in ground control and safety. Hydraulic fracturing transforms the roof structure and controls the roof caving above the working face. A framework of theory and technology for controlling hard roof by hydraulic fracturing were put forward. The typical oblate spheroidal morphology and spatial reorientation propagation morphology of hydraulic fractures were revealed. Additionally，the influence of the differences of principal stresses，water injection rates，bedding plane and pre-existing fissures on the propagation of hydraulic fractures were presented by using the experimental system of true triaxial hydraulic fracturing. The principle of the breaking location of overhanging hard roof for directional hydraulic fracturing was identified according to the stress and strain conditions of the surrounding rock and the effect of roof control. The time-space relationship and the determination method of directional hydraulic fracturing for rock mass affected by the mining were presented. The systematic methods of controlled fracturing such as the directional water jet slotting fracturing was suggested to control the crack morphology. On this basis，a complete set of equipment for high pressure(60 MPa) hydraulic fracturing have been developed to implement in underground coal mine. The hard roof caved timely and fully by controlling the extension of the main hydraulic fractures and wing cracks and the wetting effect due to water absorption. It also achieves the weakening of surrounding rock，the stress transformation，and the coal crushing by inducing ground pressure. A complete set of techniques was developed to solve the problems caused by hard roof，including the control of hanging roof in the face end，hanging roof in the opening cut，hanging roof in the central section of working face，hard top coal weakening，gas ultralimit in the initial mining stage of longwall mining with top coal caving，rock burst and large deformation in gob-side entry. The complete set of technology and equipment has been adopted in Datong coal mining area and Shendong coal mining area. Compared to the traditional methods of weakening the hard roof by blasting，the hydraulic fracturing is more advantageous. It is easy to manage，has less disturbance to the surrounding rock，requires less engineering work. It also works at large scale，long-distance control，and costs 10% less than the cost of explosive blasting.

Seismic waves induced by blasting influence the rock masses of slopes significantly. The national safety regulations for blasting (GB 6722—2014) specifies the permissible value of the blasting vibration velocity of the slope rock，but the theoretical basis of the value is not clearly stated. The dynamic stress and the vibration velocity field in rock slopes induced by blasting seismic wave were analyzed，and the mathematical relationship between the dynamic stress and vibration velocity of rock mass was proposed. To insure that the shear and tensile failures do not take place in rock masses，the threshold of the blasting vibration velocity of the slope surface was proposed based on the simplified slope model considering the classification characteristics of the slope rock and the slope structure. The strength of rock mass，the dip angle of slope，the depth of sliding surface and the frequency of seismic wave all have a significant effect on the threshold vibration velocity. The range of the allowable blasting vibration velocity of different classes of rock mass is proposed according to the mechanism of shallow landslide. The calculated threshold of the blasting vibration velocity under the condition of no shear failure is close to the control criteria of the safety regulations for blasting (GB 6722—2014). The threshold of the blasting vibration velocity of different classes of rock mass is similar to each other when there is no tensile failure. The safety threshold of blasting vibration velocity for rock slopes in safety regulations for blasting (GB 6722—2014) should be refined further on the basis of theoretical analysis and engineering practice.

Photo-elastic test was performed to analyze the evolution of force chain and block displacement in block array under a multi-stage loading and unloading cycle. The results demonstrate that both the contact force and block displacement show the visible ‘hysteresis’ during unloading. The evolution characteristics of both the contact force and block displacement indicate a critical load during unloading. A serial contact model was established to simplify the contact state of the block column transmitted by primary force chain，which reveals that the residual contact force depends on the lateral friction resistance，including the inter-particle friction and inter-particle lock. The contact force acted on the representative block was quantified by fringe analysis to achieve the evolution of lateral friction resistance on primary force chain during loading and unloading. The lateral friction resistance is positively associated with the applied load，indicating that greater inter-particle friction and contact resistance induced by the inter-particle lock are activated to resist the increasing applied load. The difference of lateral friction resistance under the same applied load between loading phase and unloading phase is the mechanism of residual contact force in block array.

The reinforcement of fully grouted bolts is widely used in slope engineering due to its proven efficacy and low cost. Based on the newly proposed approach of stability analysis of counter tilt rock slopes upon flexural-toppling failure，a mechanical model of such slopes reinforced by fully grouted bolts was established. The formula of slope safety factor after reinforcement was given. In addition，the comparison between the theoretical method and discrete element method(UDEC) was made. The simulated results are consistent with those obtained with the analytical method. The optimal reinforcement position is located in the superimposed toppling zone and the precise location is related to the parameters of slope and anchoring. Reducing the angle between the bolt and discontinuity can make the full use of the shear resistance of bolt.

In order to compare the dynamic mechanical characteristics of salt rock and mudstone interbed，the salt rock and mudstone interbed from Yingcheng were studied with the split Hopkinson pressure bar(SHPB) apparatus under triaxial confining pressures of 5，15 and 25 MPa. The formula for the dynamic strength of salt rock and mudstone interbed were derived by data fitting according to a simplified strength-strain rate model on competition between the mechanisms of thermal activation and the macro-viscosity. The results show that the salt rock and mudstone interbed are sensitive to the strain rate，that their peak stress and ductility increase as the strain rate increases，but that the strengthening effect of strain rate under the low confining pressures(such as 5 MPa) is more obvious than that under the high confining pressures(such as 25 MPa). The confining pressure effect on the mechanical behavior of salt rock and mudstone interbed under the dynamic loading condition is less obvious than that under the static loading condition. The dynamic increasing factor(DIF) decreases as the confining pressure increases，and the confining pressure effect of mudstone interbed is smaller than that of salt rock. The formula for dynamic strength fits data well with the average relative errors of 2.51% and 6.58% for salt rock and mudstone interbed respectively.

The bedding rock slope was studied in order to effectively predict its deformation and failure induced by underground mining in mountainous area based on the probabilistic integration on mining subsidence of horizontal surface. A model for predicting the subsidence and deformation of bedding rock slopes was established under the condition of unit mining and semi-infinite mining and a calculation process was presented. The predicted results were compared with the data from field test and physical modelling test. The predicted results are in good agreement with the measured data of subsidence. The shape of the predicted subsidence curve is similar to that from the physical modelling test and they have the same maximum values of subsidence.

In the traditional convergence-confinement method，bolts are usually considered as support structure，and the characteristic curve of supporting bolts is then derived individually. However，the support system cannot be constructed with the bolts only and must be constructed by combining the bolts with the rock mass. In this paper，the effect of bolt reinforcement on rock mass was considered. The analytical solution of the ground characteristic curve for bolted circular tunnel was derived with the homogenization method based on the theory of elasto-plasticity. The results of the analytical solution were compared with the ones from the numerical simulation. The proposed analytical solution of ground characteristic curve for bolted circular tunnel agrees well with the calculated results of FLAC3D. It was thus concluded that it is reasonable to combine the bolts with the rock mass as the composite bearing system. The accuracy of the proposed method was verified. Comparing with ground characteristic curves of unreinforced rock and bolted rock shows that bolts have the significant effect on the deformation of rock mass. The prestress and initial supporting time of bolts were considered in the proposed analytical solution. This study provides a relatively simple and rapid method for stability analysis of bolted tunnel.

In order to obtain the reasonable layout of roadways in the upper coal seam，the morphology characteristics of fractured zone and the concentrated stress distribution in surrounding rock induced by the mining of lower coal seam were studied with the methods of theoretical analysis，field testing and numerical simulation. This study was based on the upward mining of #2 and #4 close coal seams in No. 6 mining district of Zhaizhen mine. The results showed that the fractured zone was developed upward with the strata group as a unit under the condition of overlying composite strata structure and this forming mechanism was also verified in the field testing. The spatial morphology of fractured zone presented an irregular saddle shape tilted to the inside of the goaf with a boundary angle of approximately 75°–78°. The sub-regional rupture characteristic from bottom to top within the fractured zone was obvious. The upper #2 seam belongs to the general crack area located at the top of fractured zone. The roadway set in this areas is feasible. According to the results of numerical simulation，the broken position of the upper #2 seam was about 3–5 m on the goaf side，and the range of internal stress field was 6–10 m on the goaf side. Two schemes of roadway layout of inner stagger mode and outward stagger mode were proposed in upper coal seam based on the comprehensive study to the height，shape and sub-regional rupture characteristic of the fractured zone and the concentrated stress distribution. This layout effectively avoided the influence of fractured zone and concentrated stress field. The field application achieved good effect.

为实现煤矿冲击地压的主动区域性防治，提出先裂后注冲击地压防治技术。首先，对常规冲击地压防治技术进行分类，分析常规冲击地压防治技术6个方面的局限性；其次，探讨先裂后注对煤层的作用过程，以及先裂后注防治冲击地压的机制；然后，总结硬煤压裂和软煤压裂2个现场试验的成果，分析先裂后注防治冲击地压的效果；最后，讨论先裂后注冲击地压防治技术的不足，以及现场可能出现的问题及相应原因。研究表明，先裂后注对煤层的作用包括裂化煤层和湿润煤层，其中裂化煤层能够起到弱化蓄能能力、均化应力、孤立冲击体的作用，宏观上改变了煤体的完整性和应力分布特征；湿润煤层能够降低煤层冲击倾向性，细观上改变了煤体的脆性、储能与耗能特性。研究结果对推广应用煤层压裂技术和实现冲击地压主动区域性防治，具有十分重要的意义。

The geometric parameters of rock discontinuities are important for stability and permeability analysis of rock mass. The intelligent identification and properties calculation of rock discontinuities based on the improved algorithm of region growing and analytic geometry were made according to the nodded cloud data of exposed rock measured with the terrestrial laser scanning. To identify the rock discontinuities from nodded cloud data  effectively，the region growing algorithm was improved by specifying the normal vectors to the nodes as the judgment indicator and setting two thresholds(smoothness detection threshold   and region growing threshold  ). The orientation，spacing and scale of rock discontinuities can be computed using the analytic geometry. The effects of two thresholds on the identification results were investigated，and a suggestion for threshold selection was provided according to the difference of normal vectors between the adjacent discontinuities. Additionally，the proposed method was applied to two cases，regular planes and road slopes，to verify the robustness of the algorithm.

The systematic investigation on the strength and environmental safety properties of the SPB and SPC stabilized soil is presented in this paper. The field soil which has been industrial contaminated with nickel(Ni) and zinc(Zn) is studied. The SPB binder is composed of superphosphate and cement-activated steel slag and the SPC binder is composed of superphosphate and quicklime. The stabilized soils were tested for the unconfined compression strength，dry density，soil pH，acid neutralization capacity，toxic leaching characteristics and contaminant speciation varying with dosages and curing periods. The results demonstrate that the addition of two binders increases the unconfined compressive strength and soil pH，but reduces the toxicity leaching concentration of Ni and Zn. These results are interpreted based on the variations in chemical speciation of Ni and Zn and the capacity index of acid buffer of the stabilized soils. It was also found that the SPC stabilized soil had a lower pH value than that of PC under curing of 28 days. The SPC shows higher immobilization efficiency than PC at early curing. Overall，this study demonstrates that the SPB and SPC binders have positive effects on the immobilization of the heavy metal and the strength of the stabilized soils.

Because the end-bearing pile has a large supporting stiffness，a small vertical deformation under the normal working load on the top of the pile will not activate the pile-soil interaction. As a result，the natural bearing capacity of foundation soil is not fully utilized. The typical project presented in this paper successfully solved the problem of pile-soil interaction of pile foundation with large supporting stiffness，and also optimized the stiffness distribution in the piled raft system. The process of the design and numerical analysis are described in detail. The field test data and analytic results were compared and analyzed to verify the rationality and reliability of the piled raft foundation applied with controllable stiffness. The results of numerical analysis and field test show that the total settlement and differential settlement of the building meet the design requirements after adopting the piled raft foundation with controllable stiffness. The foundation soil bore 63% of the superstructure load and the number of the piles significantly is reduced.

The water supply project in Northern Xinjiang traverses the Junggar Basin from north to south. The open canal in Gurbantungut Desert is 166.5 km long. In the 1990s，a series of theoretical research，experiments and engineering practices were carried out regarding the field layout of canal line，sand foundation compaction，canal bed strengthening，wind prevention，sand fixation and eco-environment protection et al. After twelve years of operation and monitoring，the following conclusions are drawn through systematic analysis and evaluation：(1) the mode of the concentrated band arrangement for canal，shelterbelt，and road on platform has the advantages of small disturbance to desert，high efficiency in mechanized construction and management. The rolling and compaction technologies of sand foundation，wind-blown sand of canal bed and sand-gravel cushion resolved the technical problem for soil compaction and the compaction of two types of soils in the canal slopes simultaneously in the desert. (3) Using the soil water in the suspension wet sand layer，a biological sand control belt of 110 km long has been built with the mechanical sand fixation and biological sand control. A comprehensive sand prevention technology system including the wind prevention，sand fixation，deceleration of the sand and stepped sand blocking has been constructed. (4) The migration paths of wild animals are guaranteed. Using the biological sand control technology system，the vegetation landscape has been constructed along both sides of the canal. The biodiversity has been increased by improving the conditions of drinking water. A green ecological corridor has been built in the Gurbantungut Desert.

An approximate solution to the differential equations of axisymmetric unsteady well-flow was derived to assess the water level and discharge based on Boltzmann transformation，which can predict the variation of water level and discharge of a fully penetrating well in the infinite confined aquifer under unsteady well-flow condition caused by fixed-drop pumping. The effect of well diameter was taken into account in the solution. The relative error of the approximate solution to the classical solution is 0–15%，and the approximate solution is simpler and more convenient than the classical method. The applicability of the approximate solution was verified through a case study. The results showed that the approximate solution is identical with data in the case.

The dense coarse grained soil has the content of fine particles generally between 25% and 35% and has excellent mechanical properties. However，the seepage failure like piping or boiling cannot be easily discriminated. After a series of tests on seepage deformation，a parameter called the “equivalent specific surface area ”reflecting the specific surface area(S0) and tortuosity(T) was introduced based on Kozeny-Carman equation and measured permeability coefficient(K). A model of equal diameter capillary with porosity(n) and S'0 was established. A new criterion called the“equivalent permeability & average diameter method”for assessing the type of seepage failure of the transitional coarse grained soil was proposed according to the capillary diameter(D) and characteristic particle sizes of gradation curve(d3). The relationship between T and n of the transitional coarse grained soil was discussed on the assumption of uniform sphere particles. The gradual increase of density will lead the transitional coarse grained soil to have the continuous piping being transformed to the discontinuous piping and finally into boiling. Unlike the current“pore diameter method”and“variable cross-section method”ignoring the tortuosity or considering only the constant tortuosity of uniform soil，the parameter D controlled by is able to reflect the effect of actual tortuosity on permeability. The predicted results according to the proposed method are the same as the experimental data. The calculated tortuosity T1 increases linearly with the decrease of n，reflecting the actual growth of seepage length.

At present，there are almost no reports on the field measurement of the prestressed high-strength concrete(PHC) pipe pile subjected to negative skin friction. To reveal the characteristics of negative skin friction on PHC pile piles，the measures of installation of and protection to the fiber Bragg grating sensors(FBG) on the PHC pipe piles were studied and the strains of 4 piles of a building foundation subjected to negative skin frictions induced by the recent soil filling were monitored for 21 months. The axial forces of the piles were deduced and their variation curves were plotted. The distribution and variation features of the axial forces of the piles under the loads from the superstructure and the negative skin frictions were analyzed. The measured values of the drag loads induced by the negative skin frictions on the PHC piles were notably greater than the values calculated according to the current Chinese code-Technical Code for Building Pile Foundation(JGJ94－2008)，indicating that the current theoretical method still needs to be improved. In the strata with non-uniformly distributed soft and stiff layers，the negative skin and positive skin frictions might occur alternately and how to consider this kind of circumstance in theoretical calculations is worth studying. The quality of and avoiding the construction damage to the asphalt coating are the key to ensure the effective reduction of the negative skin friction.