Abstract:In order to compile a calculation standard for the horizontal shear capacity of the low-rise assembled wall under a new horizontal connection form,the research team carried out different conditions on 51 walls,and the paper sheared 15 of them.The results show that the shear failure of grouted wall has brittle failure characteristics;the shear bearing capacity increases with the increase of axial compression ratio;the roughness of the upper surface of grounded beam and the lower surface of wall plate have an important influence on the shear bearing capacity of specimens.Finally,based on the test results,the relevant parameters of bearing capacity calculation in the existing literature are deduced.The formula will provide a theoretical basis for the calculation of the bearing capacity of walls with edge members.

Abstract:It is very important to calculate the active earth pressure of cantilever retaining wall under earthquake. To analyze the active earth pressure distribution of cantilever retaining wall under seismic load,by applying the proposed dynamic method and considering the impact of variation of horizontal and vertical earthquake force on seismic active earth pressure, the calculating formulas of the critical Angle of rupture and seismic active earth pressure were deduced,and the influence of parameters on the seismic active earth pressure coefficient and the critical Angle of rupture were also investigated. The results show that the second critical fracture Angle increases with the increase of the vertical seismic force coefficient and decreases with the increase of the horizontal seismic force coefficient. The active earth pressure increases with the increase of horizontal and vertical seismic force coefficients.

Abstract:Based on the TS13 section of the Taizhou Bay Bridge and its connection project in Zhejiang Province,the effect of the transition from the abutment to the common section was studied. Field tests were conducted to study the soft foundation treatment scheme with variable length of pipe pile and combination of pipe pile and cement mixing pile. It is found that the smooth transition from abutment to the common section can be realized by controlling the change of pile length. Setting reasonable length and space between pipe pile and cement mixing pile,or increasing the length of transition section,can offer a smooth transition between the treatment section of pipe piles and cement mixing piles in the soft foundation treatment of pipe pile and cement mixing pile.

Abstract:The Xiashu soil slopes in Zhenjiang area collapse in different degrees caused by the moisture content change of atmospheric influence layer.The shear strength parameters under different moisture content of Xiashu soil taken from Zhenjiang Paomashan slope are measured by direct shear test.The atmospheric depth of Xiashu slope is determined by using field grooving test.On the basis of the above,the stability of Xiashu soil slopes considering the influence of water content change is analyzed by using finite element limit analysis software OPTUM.The computing results indicate that the sliding surfaces of Xiashu soil slopes gradually change from the deep layer to shallow layer with the increase of water content.The absolute attenuation rate of lower and upper limit safety factors of Xiashu soil slopes reaches about 17% with the increase of moisture content.

Abstract:Four types of open graded friction courses (OGFC) Marshall compacted samples with different air void contents were scanned with the X-ray computed tomography (CT). The air voids were obtained through digital image processing (DIP) of two-dimensional images. The difference of the air voids distribution on the horizontal and vertical section of the OGFC sample was analyzed. The horizontal and vertical cores were obtained by drilling the Superpave gyratory compactor (SGC) sample respectively. The permeability coefficients along twelve directions on the horizontal and vertical plane of each core were tested respectively using a developed constant head permeameter and a proposed permeability anisotropy test procedure. Results show that the air void on vertical section of the OGFC sample has more uniform size,content and quantity than that on the horizontal section. OGFC mixture has more interconnected air voids in the radial direction as compared to the vertical direction. Permeability anisotropy is existed inside the OGFC mixture. The degree of permeability anisotropy on the vertical plane is more than that on the horizontal plane of OGFC mixture. On the vertical plane,the permeability in the horizontal direction has the maximum value;while the minimum permeability was found when the water flow was in the vertical direction of SGC sample.

Abstract:In order to analyze the reinforcement effect of freezing method in shield tunnel construction,the steady temperature field around a single freezing pipe is analyzed based on the shield tunneling project of Dadongmen Station of Hefei Rail Transit Line 2 and a three-dimensional numerical model is established according to the actual situation of the project. The results show that the temperature field in the freezing curtain develops circularly around the freezing holes and diverges around them after the intersection of the holes occurs. And the freezing method has a better reinforcement effect that the ground settlement of tunneling construction can be significantly reduced with a maximum 50% reduction. Besides,the left tunnel has larger segment stress after the construction of the right tunnel,so the lining should be put into effect in time and the supporting system should be closed timely to ensure the safe and smooth construction.

Abstract:From the point of ecological restoration,a new way of river treatment in urban fringe area are explored to solve the problems of river environment in the process of urbanization in China. Based on the analysis of the basic characteristics of landscape ecology in urban fringe areas,these repair strategies proposed in this paper such as the longitudinal connection of river water body,the treatment of water quality of river system,the naturalized restoration of river curve,the construction of hierarchical ecological landscape,the landscape constructed wetland of beach land and the sustainable plant allocation are expected to provide a reference for landscape ecological restoration in urban fringe areas.

Abstract:The calculation of rubber dam bag is low in efficiency and limited in precision. For the limitation and shortage,this paper puts forward the calculation method of the rubber dam bag based on numerical integration,and uses two numerical integration methods to solve the first and second types of elliptic integral and apply them to the calculation of rubber dam bag. The two methods have achieved high precision. The program compiled by the algorithm can calculate the parameters and coordinates of dam bags accurately and quickly,and automatic drawing of rubber dam bag curve is realized by AutoCAD Automation technology. The research provides effective technical support for the technical research and comparison of rubber dam.

Abstract:In order to reveal the mechanical properties and internal laws of rock and soil mass from a deeper perspective,many scholars have carried out researches on the pore structure of rock and soil mass. Electronic computed tomography (CT) is the most commonly used method for quantitative observation of pore structure of rock and soil mass in recent years. In this paper,CT scan images of clay soil,rock and foamed concrete were used to calculate the fractal dimension of pores by gray scale method and binarization method respectively,and the relationship between the porosity of rock and soil mass and the fractal dimension of pores was studied,and the characteristics and applicability of the two methods in the study of fractal characteristics of pore structure were compared and discussed. The results show that the treatment effect of binarization depends on the selection of threshold value,and the threshold value calculation method based on the original porosity of sample is simple and effective;However,the grayscale method preserves more original image information. For different geotechnical materials,the relationship between porosity and fractal dimension of pores obtained by binarization method is related to a good power function. When gray scale method is used,the fractal dimension of rock and soil mass presents a slight increase trend with the increase of its porosity,which is approximately linear. In general,the two treatment methods can be used to study the fractal characteristics of the pore structure of the rock and soil mass,but each has its advantages and disadvantages,and the appropriate method should be selected according to the research object.

Abstract:Physical property indexes of coastal saline soil and improved coastal saline soil such as specific gravity,plastic limit,liquid limit,plastic index,maximum dry density,optimal water content were studied through laboratory experiments in this paper. Based on unconfined compressive strength test,the unconfined compressive strength of improved saline soils at the curing age of 7 d,14 d,28 d and 60 d were studied. Taking the improved saline soil samples at the curing age of 14d as an example,the stability of the improved saline soil under different soaking time (1 d,4 d,7 d,14d) was studied. The test results show that some indexes such as specific gravity,liquid limit,plasticity index and maximum dry density decrease linearly with the increase of the total content of the admixture;other indexes such as plastic limit and optimal water content increase linearly with the increase of the total amount of admixture. The unconfined compressive strength of improved saline soil increases with the increase of curing age and total admixture content. The unconfined compressive strength of improved saline soil decreases with the increases of immersion time. The unconfined compressive strength of improved saline soil increases linearly with the increase of the total amount of admixture. The water stability coefficient of each ratio increases with the increase of curing age. With the increase of the total amount of admixture,the stability coefficient of unconfined compressive water of improved saline soil basically increases linearly. With the increase of soaking time,the range of mass loss rate becomes larger and larger. With the increase of the total amount of admixture,the loss rate of modified saline soil basically decreases as a power function.

Abstract:In the sea embankment filling project,in order to find out the suitable mixing ratio of silt and sea sand,The methods of drying and adding quicklime was used to reduce the water content of the silt,and finds the moisture content which is easy to be broken and even. According to different quality ratio and different test regulations,samples are prepared,and different curing age is designed.In the corresponding age,direct shear test,compression test,unconfined compressive strength test and penetration test are used to select the appropriate mixing ratio for the actual project. The results show that the cohesion basically reaches the peak value,when the mixing ratio of sea sand and lime soil is 1:2,and the internal friction angle decreases with the increase of the proportion of lime soil. After curing for 28 days,it is close to the low compressibility soil,which also meets the engineering of low permeability requirements.

Abstract:The elastic membrane generated from the reaction between polyurethane stabilizer and water can effectively improve the strength of sand. In order to study the effect of temperature on the improvement of polyurethane stabilizer,unconfined compression test was carried out. The variation of sand strength with different density and polyurethane stabilizer content at different temperatures was analyzed and the influence mechanism of temperature is analyzed in depth. The test results show that temperature has obvious influence on the improvement of polyurethane stabilizer and the unconfined compressive strength increases with the increase of density and polyurethane stabilizer content at constant temperature. When the temperature is higher (≥ 35℃),soil moisture decreases and the cured film shrinks causing the increase of its elasticity and strength,which can greatly improve the the strength of sand. When the temperature is lower (≤ 10℃),the cured film is frozen and the strength increases,which can further improve the strength of the sand;Under two extreme temperature conditions,the effect of polyurethane stabilizer is improved,but the effect is more obvious at high temperature.

Abstract:The slope of the excavations often has the concrete surface layer and the hardened slope top which is impermeable to water. In order to study the effect of rain type and the length of hardened slope top on the stability of the unsaturated excavations,the rainfall simulation is obtained by GeoStudio SEEP/W module,and the distribution characteristics of the water pressure and volume moisture of the slope after the rain are obtained. Then,the rain simulation results are imported into the SLOPE/W module. The shear strength parameters obtained by the consolidated quick shear test are used in numerically calculation,and the stability of the excavations is evaluated. The results show that the depth of infiltration of instantaneous heavy rainfall is small,and the infiltration depth of ordinary rainfall is large in long periods. The hardened slope top tends to limit the infiltration of rainwater,reduce the infiltration at the slip surface,and is beneficial to the stability of the excavations. When the slope top hardening length is 3 m,the effect of rainfall on the stability of the excavation is not obvious,and when the length is 5 m,the stability of the excavation is basically not affected by rainfall. When the initial water content of the soil of the slope is low,instead of arousing adverse effect on the stability of the excavations,the early rainfall is beneficial to the stability of the excavations. Finally,taking the actual landslide as examples,the simulation results are verified and the importance of slope top hardening to the stability of the slope is explained.

Abstract:In this paper,a series of direct shear tests were carried out on cultivated ryegrass-reinforced undisturbed clay,the effects of root content and water content on shear strength properties of reinforced clay were studied comparatively,and the mechanism was analyzed according to the research results. The test results show that with the increase of root content,the shear strength and cohesion of reinforced soil gradually increase,and the change of internal friction angle is slight. This is induced by the presence of roots which strengthen the friction between soil particles. Moreover,the root elastic deformation occurs in the process of shearing,and the internal tension stress of root is transformed into the force that resists the displacement of soil by friction. It is therefore the strength of soil is enhanced. With the increase of water content,the shear strength and cohesion of the reinforced soil decrease,and the internal friction angle changes little. This can be attributed to that,on the one hand,the presence of water reduces the pull-out resistance of roots and the friction resistance between soil particles,and on the other hand,the increase of water content leads to a decrease of matrix suction,which reduces the strength of liquid bridge between soil particles,thus reducing the shear strength of soil.

Abstract:In order to study the mechanism of the influence of particle size on the start-up of slag debris flow,we took four debris flow gullies in Tongyu gold mining area of Shaanxi Province as the research objects. Through field investigation,laboratory test and numerical simulation,we revealed the mechanism of the influence of particle size on the start-up process of slag debris flow. The main conclusions reached are as follows:with the increase of fine particle content,the shear strength and permeability of slag decrease,and the effect of saturation state is more significant;the macro and microcosmic parameters of each grading slag are obtained by laboratory and numerical experiments;the grain grading of the slag can change the shear strength and the permeability of the slag body,and then influence the stress condition and the structure failure mode of the slag,and finally influence the start-up difficulty of the slag-type debris flow.

Abstract:Changes in the basement tends to cause the overburden to rupture and deformation and damage to structures such as surface structures,underground pipelines,and tunnels. In order to explore the development process and mechanism of basement extensional ground fissures,this paper reveals the variation law of deformation and displacement of overlying soil caused by basement extension through physical simulation experiments,and analyses the section structure characteristics of fissures and the development and fracture process. The results show that under the tensile stress of the substrate,the overlying soil on the fault will be"pushed"to release stress. With the continuation of horizontal tension,the settlement and thinning of overlying soils occur first,and especially,the response of soils with strong plasticity is more obvious. Under the action of continuous stress,cracks extend from bottom to top until they penetrate the surface. In addition,the closer to the ground fissure,the larger the amount of sedimentation and thinning of the soil is,and the smaller the density becomes.

Abstract:In order to reveal the impact of mining in the north piedmont of Qinling Mountain on the ecological environment,combination of on-site investigation and remote sensing interpretation was used in this paper to investigate the geological environment of the mine. The geological environment conditions,the development of geological disasters and the present situation of damage control were selected as the intermediate variables. Each of intermediate variables includes microgeomorphology,hydrogeology,strata lithology;collapse disaster,debris flow disaster;waste slag pressure occupation status,land reclamation status and disaster prevention and control status. The effect of each impact factor was determined by analytic hierarchy process (AHP) and combined with the spatial analysis function of ArcGIS carrying out mine geological environment assessment and map division.The results show that the piedmont of the mountain where the mountain and the platform in the study area are in contact with each other is poor in stratigraphic lithology,and the collapse disaster is serious. The problem of waste slag in the area along the eastern province of 202 is serious and the debris flow disaster is developing.The comprehensive evaluation of the geological environment in the mine area is mostly medium or poor,and the environmental condition along the 202 provincial road is particularly bad. This evaluation result is in good agreement with the field investigation results of the north piedmont of the Qinling Mountain. The evaluation results can provide theoretical basis for the government and other relevant departments to carry out mine geological environment governance and restoration.