通过大型振动台试验，研究反倾和顺层两类结构岩体边坡在强震条件下的地震动力响应。结果表明：强震条件下，斜坡对水平地震动力的响应要远超过垂直地震动力，前者所导致的加速度响应峰值(PGA)放大系数是后者的2～3倍。在水平地震动力作用下，斜坡的地震动响应具有显著的高程效应和结构效应。对于硬岩顺层斜坡在1/2倍坡高以上坡面和坡内均出现显著的PGA放大效应；而硬岩反倾斜坡的放大效应则主要表现在坡体内部1/2倍坡高以上和坡体表部2/3倍坡高以上，且放大幅度要高于顺层斜坡。软岩斜坡在水平地震力作用下的动力响应总体上较硬岩斜坡弱，顺层斜坡表现为1/2倍坡高后，PGA放大系数的持续增大，而反倾斜坡主要表现为坡表中下部(1/4倍坡高处)和3/4倍坡高以上PGA的突然增大。模型在强震条件下的破裂观测结果表明：硬岩顺层斜坡(HD)在变形破坏通常表现为顺层滑移–下部隆起溃屈型失稳；硬岩反倾斜坡(HAD)为后缘垂直拉裂–中下部平缓剪出型失稳(L型滑面)；软岩顺层斜坡(SD)为顺层滑移–底部挤出–分层滑移型失稳；软岩反倾斜坡(SAD)为斜坡顶部拉裂–下部剪出型失稳。试验结果与现场观察现象能较好吻合，从而深入揭示强震条件下层状结构斜坡的地震动力响应和失稳破坏机制。

In the stability analysis of underground caverns，the stress state on key parts of surrounding rock of the cavern?s cross-section is essential，and it is obtained by the geostress measurement and analysis. The geostress measurement is time-consuming and costly，especially in the high geostress region，it is more difficult to obtain reliable measured data；therefore there is often lack of an important basis for the stability analysis of underground cavern. The critical information to evaluate cavern stability is stress state of the wall rock on the cross-section，so the stress state measurement adopting slit local stress relieving method on the key parts of the wall rock is suggested；the two-dimensional stress state on rock wall can be determined provided gouging of more than 3 narrow slots of different directions on the measured site and measuring the deformation caused by the gouge. After the slit rock elastic modulus test in the site，the test results are widely applied，i. e. continue improving pressure of steel pillow buried in the narrow slot in the test，until the displacement caused by it offsets the displacement caused by gouging narrow slot，hypothetical normal stress on perpendicular bisector of the narrow slot is measured；and then to calculate the wall stress of surrounding rock；as a supplement to the measured wall rock stress by slit local stress relieving method and confirm each other. Good result is obtained in the example of engineering application.

Solid-fluid interaction between surrounding rock and water body has significant influence on the stability of subsea tunnel. It is necessary to analyze the solid-fluid interaction involved in the construction of subsea tunnels using a model test. According to the feature of solid-fluid coupling model test，a new type of system for solid-fluid coupling model test was presented to simulate the quasi-3D plane stress and plane strain. The model test system was designed as 3.4 m in length，3.0 m in height and 0.8 m in width，and composed of rack body with steel structure，test chamber with toughened glass and loading devices of water pressure. The steel structure rack body consists of 6 steel structure members operated independently and connected by screw bolts with high strength. Toughened glass was used to assure leakproof of the test chamber and easily inspect the seepage and deformation of surrounding rock during subsea tunnel construction process. Furthermore，based on a new type of simulation material，the proposed new type of model test system was applied to the solid-fluid coupling model test for the Kiaochow Bay Subsea Tunnel. The pressure on tunnel wall，the variation of seepage and displacement of surrounding rock mass can be captured using the model test. The research methods and results will instruct similar engineering.

Based on the self-made triaxial servo-controlled seepage equipment for thermo-hydro-mechanical coupling of coal containing methane，the experimental study of mechanical properties of coal containing methane was performed on raw coal samples in No.10 Mine，Pingdingshan Coal Mining Group Corporation Ltd.，under different loading-unloading conditions i. e. increase axial pressure and unload confining pressure. The results show that mechanical properties of coal containing methane under different loading-unloading conditions are different；bearing strength of coal sample under loading-unloading is lower than peak intensity of coal sample under conventional loading；bearing strength of coal under loading-unloading decreases exponentially with the increasing of initial axial force，bearing strength decreases with increase in axial pressure loading speed which presents the power function relationship；it decreases exponentially with the increase in initial confining pressure，it decreases with increase in gas pressure which presents the linear relationship；with increase in axial strain，deformation modulus under different conditions presents the trend which decreases rapidly first then decreases slowly until to remain approximate stable after failure；the Poisson?s ratio exhibits the tendency that first decreases then increases and maintains stability at last. The research has an important guiding significance on tunnel supporting and gas extraction.

The structure of the deep borehole hollow inclusion strain gauge geostress measuring instrument and its assistive tools are described，which were used for deep borehole geostress measurement；and an example is given. Traditional instrument based on stress-releasing theory is only applied to shallow borehole，not applied to deep borehole. The traditional instrument is improved，and a deep borehole hollow inclusion strain gauge geostress measuring instrument is developed. It integrates hollow inclusion strain gauge，strain recording apparatus and electronic compass into a micro-probe，which can be installed at predesigned position in the borehole when measuring the geostress. Geostress data of Zhangjiang observation borehole in Shanghai at the depth of 365 and 385 m underground by using this technology is obtained. The results show that the maximum principal stress direction in surveying area is near EW direction；and the values of the maximum principal stresses are between 8.5 MPa and 9.0 MPa. The minimum principal stress direction is near vertical；and the values of the minimum principal stresses are near equal to the overburden pressure. Measurement results show that deep borehole hollow inclusion strain gauge geostress measuring instrument is suitable for deep hole of 3D geostress measurement.

The shear mechanism of pile-rock interface of rock-socketed pile includes sliding dilatancy and shear slipping；the sliding dilatancy causes the normal stress increase significantly. The method for calculating the side friction of rock-socketed pile proposed by Serrano did not consider the effect of pile-rock interface dilatancy，which makes it more conservative than the measured value. Based on the results of the structural plane shear tests under constant normal stiffness(CNS) condition，which fully consider the effect of lithology，pile diameter and construction on the mechanical characteristics of rock-socketed piles，and the quantified values of the normal stress increment produced by dilatancy are achieved；then Serrano?s method is modified by considering the quantified normal stress increment values. The analytical results show that，the side friction values calculated by the modified method exceed the values calculated by Serrano?s method；and the former are also closer to the field measured values. It is confirmed that the modified Serrano?s method is more reasonable.

Paste made of tailings and waste rocks was used to backfill the subsidence caused by mining in a certain mine. The strength of paste is directly related to the effect of the disposal and safety production underground. The content and grain size of waste rocks are key factors influencing shear strength. In this regard，a test is performed on the test block of disposal body with the modified small direct shear apparatus so as to gain the influence law of the disposal body?s shear strength，cohesion  and internal friction angle  ，which are related to the waste rock?s content and grain size. Its strength mechanism is analyzed with the modified adhesion theory of friction. The test result shows that，as the content of waste rock increases，the value tends to decline and the value tends to increase；the shear strength may be divided into cohesive force control，combined control of cohesive and friction and friction control according to the waste rock content and its grain size；the shear strength tends to drop before increasing as the content of waste rocks increases，and reaches its minimum value when the content is between 20% and 30%；the shear strength increases with the grain size；the stress-strain curve shows strain softening in low stress zone and strain hardening in high stress zone. The contribution of friction strength to shear strength reaches 80%；and the macro shear strength depends on the shear strength between grains；the change of waste rock?s grain size and content actually changes the contact area between the grains of the disposal；so that it changes the friction strength between grains and thus changes the macro shear strength.

Underground salt rock storage cavern is widely used for its good sealability and safety performance，but the research on its system reliability and risk is still at the exploratory stage. Based on the system reliability analysis theory，the failure of storage group is defined in this article. Considering the influence of the cavern?s volume shrinkage and pillar?s plastic zone development resulting from salt rock?s creep property during operation period，the multiple failure modes of the storage group are given and the system reliability mode is built. Considering the correlativity of different elements and using the weakest failure mode assumption，the time-variant system reliability of underground salt rock storage group is analyzed. Based on Jintan salt rock storage group，a salt rock storage group numerical model is established and its time-variant system reliability is studied，and some valuable conclusions are obtained. A method of time-variant system reliability analysis is proposed and the result can provide reference for the safe operation and stability evaluation of the salt rock storage groups.

The change of rock internal microstructure along with temperature increasing leads to the variation of physico-mechanical properties. The experiments on physico-mechanical properties evolution of granite were carried out at temperature ranging from room temperature to 800 ℃ by using MTS servo-controlled testing machine and heating furnace. The research results indicate that：(1) The rock physico-mechanical properties change with temperature can be divided into five stages：i.e. room temperature to 100 ℃，100 ℃ to 300 ℃，300 ℃ to 500 ℃，500 ℃ to 600 ℃ and 600 ℃ to 800 ℃. The first three stages of temperature range correspond to the vaporization escaping interval of adhered water，and bound water and structural water. (2) The phsyico-mechanical parameters of rock have larger changes in temperature between 400 ℃ to 600 ℃，specially at the temperature of 573 ℃，where quartz has a phase transformation，from α phase to β phase. In this process，it is leaded to the increase of rock internal microcracks，which can be described as increasing of volume，reducing of bearing capacity，increasing of permeability，and the mutation of wave velocity. (3) After the temperature higher than 600 ℃，rock strength and wave velocity continue to reduce，which is influenced by solid mineral inflation and fracture of metallic bonding.

The uniaxial compression tests on marbles were performed under six levels of strain rates ranging from 2×10－5 to 5×10－3 s－1 by using RMT–150B servo machine. The effects of strain rate on stress rate，peak strength，elasticity modulus，Poisson?s ratio，softening modulus，strain at peak stress，storage energy，releasing energy，and fracture behavior were analyzed. The results show that the uniaxial compression process including four stages：compression，elasticity，yielding and failure stages under different strain rates. The relationship of stress rate and logarithm of strain rate could be expressed in exponential form. The peak strength of marble had a positive correlation with strain rate which could be expressed in quadratic polynomial form. The strain rate has little influence on elasticity modulus，softening modulus，and peak strain. The Poisson?s ratio has a negative correlation with strain rate，which could be expressed in exponential form. The accumulated energy prior to stress peak and released energy after stress peak has a positive correlation with strain rate；and the higher the strain rate is，the more serious cracking is. When strain rate is less than 5 × 10－4 s－1，the samples mainly present shear failure mode. The failure mode would be changed from local shear failure to overall shear failure with the increase of strain rate；and it is easier to form a cone-shape failure under high strain rate. The investigation results can provide a certain references for rockburst prevention and engineering seismic design.

Based on the particle flow theory and particle flow code(PFC)，the simulative approach of rock acoustic emission(AE) in meso-scale is established by using the moment tensor theory. This approach can simultaneously give the occurrence characteristics of AE event such as time，location and magnitude，reproduce the generation，propagation and coalescence progress of cracks，and consequently reveal the rock failure mechanism. The reliability of this approach is verified by comparing the experiment and calculation data based upon the AE characteristics test of lab granite complete failure process. Some main research results are as follows：(1) Before the peak strength，the number and magnitude of AE events are less and lower，respectively；and they are distributed randomly in the sample. From the peak strength to failure residual strength，the number and magnitude of AE events are much more and higher，respectively；and they are distributed principally along the macro fracture belt. (2) The number of AE events behaves as normal distribution with the magnitude variation. Between the mean and peak value of magnitude，the cumulative number of AE events behaves as linear log function relationship with decrease of magnitude. (3) The number of microcrack in each single AE event increases and approximatively behaves as Boltzman function relationship with increase of magnitude. (4) The number of AE events behaves as negative exponential function relationship with the number of microcrack，namely in case the kind of AE event owns less microcracks；its proportion is higher in total AE events. The research results make up the deficiencies of the existing AE test and simulation method，and can be utilized as a new approach in the research of AE test and field microseismic monitoring.

In fact，coal and gas outburst is mechanical destabilization and damage to gassy coal induced by mining under tridimensional stresses，seriously threatening safe production for coal mine. Taking the moulding coal powders of typical high-gassy coal mines，Sunjiawan coal mines in Fuxin as research object，the experiments of coal and gas outburst were made to detect rule by home-made device under tridimensional stresses including axial pressure，confining pressure and pore pressure to simulate －600 m mining. The outburst features were reproduced such as that the size of jet mouth is smaller than the radius of jet hole and the distribution of jet coal powders has sorting feature. The reliability of device was verified. According to the results，six outburst zones were divided and new understandings were presented. The mass distribution of coal powders had zone feature and existed extremal zone and mean zone. A new idea was presented to study outburst mechanism based on the jet features of gas-coal two-phase reflected in experiments. The maximum zone of mass of coal powders was located in medium long zone which was the energy dissipation zone of jet outburst of gas-solid two-phase gassy coal. The remarkable wave character was observed by the distribution of coal powders on different particle sizes. The coal powders of smaller size were main part in maximum zone of mass. The coal powders of rather large size were main part in minimum zone of mass. The coal powders of smaller size were main part in the ending of outbursting zone. It was presented that high-pressure gas is not only outbursting power but also damage power for powdered coal. The energy releasing has wave character in the process of coal and gas outburst. The conclusions can offer references to mechanism understanding of coal and gas outburst.

Multifield coupling test system for dynamic disaster in coal mine was independently developed；the system mainly consists of bearing skeleton frame，specimen box，rapid response door for sealing，servo loading system，data acquisition system and other auxiliary equipments. The test system could be used for simulation of coal and gas outburst disaster and dynamic state of stress during coal mining；its main advantages are reflected in：(1) Large size of specimen box makes simulation closer to the reality，and it is designed in high sealing pressure (up to 6.0 MPa). (2) It can provide complex loading called three-dimensional and multilevel loading，which is closer to the state of stress distribution in the underground mining. (3) Up to 64 sensors are used to collect coal/rock parameters such as temperature，stress and gas pressure of the different spatial positions，in order to research the temporal and spatial evolution of the coal/rock parameters in the process of the coal mine dynamic disaster. A successful simulation test of coal and gas outburst by using the test system was made；the result indicates that the temperature and the gas pressure in the coal seam both show diversity in temporal and spatial variation，specific performance in the rapid pressure drop and the great temperature reduction in the obvious dynamic effect area of the coal seam. So the evolution of physical field，in a manner，indicates the space-time development status of the coal seam dynamic effect. The result means much to further understand the coal and gas outburst mechanism.

A large-scale shaking table model test of a two-step slope model with the geometric scale of 1：8 was performed to study the dynamic response characteristics including seismic acceleration，seismic displacement，and seismic earth pressure of sheet-pile retaining wall under earthquake loads，respectively. In order to comparatively study the effect of the parameters such as seismic waveform，its excitation direction and excitation type on the seismic response characteristics of sheet-pile retaining wall，Wenchuan seismic wave with three excitation directions including horizontal(X) direction，vertical(Z) direction，and horizontal and vertical(XZ) direction，Darui synthetic seismic wave with XZ excitation direction，and Kobe seismic wave with XZ excitation direction were used as the excitation waves in the model test. The results show that the dynamic responses including seismic acceleration，seismic displacement，and seismic earth pressure of sheet-pile retaining wall are triggered mainly under horizontal direction excitation，and related to the seismic waveform，excitation direction，and the transducer?s location. The peak seismic acceleration response increases with the peak excitation acceleration and the height of retaining wall；and it presents obvious nonlinearity. The suitable amplification coefficient of earthquake inertia force quasi-static value must be selected in the basis of the combining form of retaining structures，slope shape and its behavior；and the seismic waveform are taken into account. The response mechanism of both the peak seismic displacement and the seismic permanent displacement present obvious nonlinearity；and the seismic displacement mode of sheet-pile retaining wall is the translation from the filling soil-mass of slope mainly under the excitation of XZ direction. The peak seismic earth pressure against the height of sheet-pile retaining wall presents obvious nonlinearity；the maximum of peak seismic earth pressure appears at the middle part of retaining wall；and the minimum at the lower or the upper.

Three kinds of experiments on water seepage were carried out，including homogeneous media physical simulation，heterogeneous media physical simulation and heterogeneous media simulation affected by mining. The regression analysis method has been used to study the relation between primary field current I and water injection Qi of the physical model. Field investigations，including geoelectrical detection and water yield measurement，have been conducted in a coal mine where a water flood disaster happened during this field work. And correlation analysis method has been used to study the relation between primary field current I and water yield Qo of the field detection area. Physical simulation experiments of steady seepage both in homogeneous and heterogeneous media have indicated that before water-saturated，there exists a linear relationship between the variables of I and Qi. Experiments of seepage in heterogeneous media affected by mining have indicated that the primary field current I presents the steady seepage characteristics，there still exists a linear relationship between I and Qi. That is to say，primary field current I mainly responds to the groundwater seepage process；while the response to rock breaking and fracturing is not that obvious. According to these conclusions，correlation analysis method has been used to analyze the field detection data；and the result shows that during the water flood period，there is a positive correlation between primary field current I and water yield of the detection area Qo. Therefore，trend of Qo can be predicted by the trend of I. Meanwhile，the electrodes with high correlations between I and Qo can help to locate the groundwater flow channels，which can support the resistivity analysis and interpretation.

It is the first time to detect the leakage channel of the dam by slug test；for that the slug test is used to get the permeability coefficient of a point. Based on the Ling?ao Reservoir project，the leakage channel of the dam is detected at the zone pile No. 0+250–295 after a series of slug tests. Using the method of temperature tracer method and detecting of electrical conductivity，it is found that the result is basically the same with the result gotten by slug test. After grouting to the zone of pile No. 0+275–295，there is an obvious effect through the reservoir water level and the flow rate of dam weir. So it demonstrates the correctness of the measuring result of slug test. There is great practical significance and broad application prospects for the application of slug test to detect the leakage passages and overhaul reinforcement of earth-rock dam and riverbank.

Slope protection is a way to prevent the debris flow. Model test was carried out to study the macro-meso mechanism of slope protection and anchors were fixed to prevent the debris flow on slope by using the anchor-slope protection. Retrogressive toe sliding is not found during the experiment；and four stages as water seepage，pore water accumulation，close-grained slide and relative stability of slope were found during test. Based on the macro digital camera，the transformation mechanism of soil including the trail of particle movement，displacement and porosity were analyzed during the debris flow on slope prevention with anchor-slope protection. The meso-analysis shows that the movement of particle was restricted by anchor-slope protection；and the porosity dropped down by 12%，and the relative stable state as fine particle drop to the bottom and compaction，the upper coarse particle skeleton is stable was formed at last. The research manifests that the probability of debris flow on slope was decreased by the effect of filtering water and holding soil of anchor-slope protection with different slope deformations and structures. The research provides a reference for the debris flow on slope prevention.

Seismic response of a new type of foundation，the composite caisson-piles foundation，is studied through a simplified analytical method. The focus is the contribution of the piles beneath the caisson in increasing the earthquake resistance of the foundation-superstructure system. Firstly，considering the interaction between the soil and foundation with dynamic Winkler model，the equation of kinematic response of the composite foundation under S-wave is derived. Secondly，a simplified model for the seismic response of the foundation-column-lumped mass system in frequency domain is built；and with Fourier transformation this method is applied to transient seismic problems. Thirdly，with an example of soil-foundation-superstructure seismic behavior，this proposed method is validated by comparison against 3D dynamic FEM modeling，in which domain reduction method(DRM) is utilized. Lastly，the significance and mechanism of adding piles in improving the earthquake resistance of the foundation and superstructure are analyzed through examples in different soil conditions. Discovery in this study is that adding piles under the caisson is an efficient way to increase the seismic resistant capability of the soil-foundation-superstructure system；and the main mechanism is the elimination of the pseudo-resonance.

Zygophyllum xanthoxylon and Caragana korshinskii are shrubs planted separately in in-situ shear test devices designed and worked out by the researchers. The dynamic variation on the shear resistance，shear strength of the soil without roots and root-soil composite systems are observed from two degrees of slope via in-situ shear test on soil without roots，Zygophyllum xanthoxylon root-soil composite system and Caragana korshinskii root-soil composite system. At the same time，the time effect of slope protection for shrubs is evaluated；and the accuracy of the in-situ shear test is proved by indoor direct shear tests. The results show：(1) At the same degree of slope，the shear resistance and shear strength of root-soil composite system are larger than those of soil without roots，i.e. plant roots can significantly improve the shear capability of slope soil. The shear resistance and shear strength of Zygophyllum xanthoxylon root-soil composite system are reflected in tension or shear of broken roots，friction between soil and pulled-out roots，anchor and friction of slipped roots，while those of Caragana korshinskii root-soil composite system from the anchor of roots and friction between roots and soil. The shear resistance and shear strength of soil without roots and shrub root-soil composite systems decrease with the slope degree increase. (2) The shear resistance of soil without roots reaches its peak value after three seconds，while that of root-soil composite system reaches the peak values after 69.8 to 168.2 seconds. The shear strength of soil without roots reaches the peak value when the displacements are within one millimeter，while that of root-soil composite system reach the peak values when the displacements are from 23.13 to 83.13 millimeter，i.e. the peak time of shear resistance and peak displacement of shear strength for root-soil composite system appear later than those of soil without roots. Those findings reflect that the tensile capability of roots and the friction between roots and soil during the process of shearing gradually transform to be the shear ability which can delay the slope deformation and failure. (3) To prove the accuracy of in-situ shear test，indoor direct shear tests on soil without roots and shrub root-soil composite systems are conducted. The shear strength values of indoor direct shear tests approach the values of the in-situ shear test，showing that the method and the results of in-situ shear test are rational. Those achievements have theoretical and practical values in constructing ecological engineering，protecting ecological environment and preventing geological catastrophes，such as soil and water loss，shallow landslide in Xining basin and the loess slopes of northeast Qinghai—Tibet plateau.

A green reinforced gabion earth retaining wall model in the cut-and-fill condition was designed and made. Its deformation，earth pressure and tensile strain of reinforcements were tested by applying hierarchical uniform loads on the wall top，combined with numerical analysis，its bearing capacity development rule and failure model were analyzed. Based on upper-bound method of plastic limit analysis，the calculating formulas for ultimate bearing capacity，safety factor and limit height of reinforced earth retaining wall in the cut-and-fill condition were obtained. The results show that，under the hierarchical uniform loads，its bearing capacity development process can be divided into initial compaction，development，yield and failure stage. The distribution form of wall top vertical settlement is triangular；and sliding instability appears along the cut-and-fill interface. The distribution law of earth pressure，deformation and tensile strains of reinforcements are affected by the failure model. The provided stability analysis method has high precision which considered the effect of reinforcements on steps.

In order to identify the influence of the thickness and layering of stratum between the pile tip and bedrock on the pile stiffness and damping，a longitudinal vibration response of single pile was obtained by a taper fictitious soil pile model. The soil in the tapered area of influence，which is extending to the surface of the bedrock，is treated as a fictitious soil pile. The pile complex impedance was obtained by impedance transfer method combining the boundary condition at the fictitious pile tip. A parameter analysis of the stratum under the pile was carried out to determine the effect of the soil under the pile on the complex impedance at both pile tip and head. The results show that，the stiffness of pile has a significant improvement，and the damping decrease，when the stratum between the pile tip and bedrock is less than 5 times the radius of the pile. The soft interlayer in the stratum under the pile will result in the decrease of the pile stiffness and increase of the pile damping；and the hard interlayer has an inverse effect. In addition，for multilayer stratum under the pile tip，a major error of pile complex impedance may be created only considering the first layer，particularly for the pile subjected to quasi-static load.

In order to study reinforcement effect in coal gangue foundation improved by dynamic compaction，the distribution and rules of the dynamic stress at different depths，effective strengthening depths under different impact loadings，a serial of physical model tests are carried out. The dynamic strain gauge DH5939 is used to record the induced dynamic stress of different tamping energies，different blows and different measuring points. It is shown that the single blow settlement decreases with the increase of the number of tamping and increases with the increase of tamping energy under the same blows. The dynamic stress has mainly a single peak，no obvious second crest，acts in a very short time and the time that dynamic stress reaches peak is less than the decay time. It has a significant decay to reach the peak under the impact loadings along the depth of the hammer. For the same depth，with increasing of tamping energy and compaction number，the dynamic stress increases correspondingly. In addition，the physico-mechanical properties of the coal gangue foundation such as degree of compaction and cohesion have greatly improved after dynamic compaction；and they increase with the increasing of tamping energy，the distance from the rammer point is more near，the increasing amplitude is more obvious under the same tamping energy. It is concluded that the best tamping energy is about 3 000 kN•m and the best blow count is 7–9 blows for meeting the actual engineering. The results are suitable for coal gangue foundations improved by dynamic compaction. These results also have a certain reference value for other loose friable media such as construction wastes.

The cyclic spherical stress is very common in the dynamic stress field of soils；however，in previous researches，it was usually neglected. Based on the dynamic triaxial tests with cyclic confining pressure，the influences of cyclic spherical stress on the strain behavior of saturated clays are studied through coupling cyclic confining pressure and cyclic deviatoric stress. Moreover，the action mechanisms are also discussed. Test results show that the existence of cyclic spherical stress not only changes the development speeds of cyclic strain，but also changes the ratios of maximum compression strain to maximum extension strain. The influences are not only related to the phase differences between cyclic spherical stress and cyclic deviatoric stress，but also related to the amplitude of cyclic deviatoric stress. When the phase angle is 180°，the compressive strain develops more quickly；and when the phase angle is 0°，the tension strain develops more quickly. Based on the test results，the action mechanisms of cyclic spherical stress on the changes of dynamic strain behavior are explained from the perspective of the total stress and the effective stress，respectively.

A series of expansive force tests of small deformation as 0，0.2，0.5 and 1 mm were conducted on the remolded samples of expansive soil in Nanning to obtain the key influence factors of the expansive force. A formula of the expansive force with initial water content and dry density was given；and small deformation expansion force variation law was analyzed. The results show that：(1) When the expansive force test shows non-deformation，the expansive force increases exponentially with dry density increases and presents a power function relation with the initial water content. (2) Test of small deformation shows that the expansive force attenuates obviously with the deformation increases；in the condition of high dry density and low initial water content，the amplitude of attenuation are larger；otherwise smaller. Under constant dry density and initial water content，the small deformation expansive force exponentially attenuates with the deformation rate increases. (3) The expansive force ratio of non-deformation and small deformation decreases exponentially with the increase of deformation rate；when the deformation rate is 1%，the ratio of small deformation expansive force to non-deformation expansive force is 75%；this ratio is 55% when the deformation rate is 2.5%；and this ratio is 35% when the deformation rate is 5%.