| In recent years,under the background of the 13 th Five-Year Plan to develop infrastructure,my country’s transportation engineering has developed rapidly.The 14 th Five-Year Plan proposes to continue to promote the construction of a strong transportation country,and the construction of high-speed railways and highways will still provide impetus for the development of the national economy.As a large number of lines pass through the mountains and mountains,the elevation drop forms a large number of high slopes,and the safety of the slope engineering is particularly important.In the overall stability design of the actual slope,the most unfavorable working conditions such as rainfall and earthquake should be considered,and the effect of the supporting structure should be studied.The general slope stability analysis uses the safety factor as an index to characterize the slope stability,and often ignores various uncertain factors such as geological conditions,soil parameter variability,and loss of support structure force.If the influence of the above factors on the slope stability is ignored,the result will have a large deviation and lead to improper design.In order to solve the above problems,this paper relies on the Xingquan Railway high cutting slope construction site,according to indoor geotechnical tests,reliability theory and finite element methods to study the slope of the high cutting slope reinforced with anti-slide piles under rainfall and earthquake conditions.Reliable performance,considering the reinforcement effect of anti-sliding piles under different conditions,and studying the design method of anti-sliding piles based on the limit state method,the main research work and corresponding conclusions are as follows:1.Based on triaxial compression and direct shear tests,the shear strengths of three soils under different water contents and different confining pressures were studied respectively.The results showed that the samples exhibited obvious strain softening under small confining pressures.The strain hardening process is exhibited under large confining pressure.The e-logp curves of the three soils are analyzed to explain the effect of consolidation on the shear strength of the samples.In general,the effect of moisture content on shear strength is obvious,and the greater the moisture content,the smaller the shear strength.The equations of c,φ and water content were fitted for the triaxial and direct shear tests,respectively,which provided parameter support for the reliability analysis below.2.The limit state idea and reliability theory are the core methods of this paper.The limit state method is simply applied through the direct shear test as an example.Reliability is 0when destroyed.Taking a mean slope as an example,the finite element strength reduction method and the finite element limit analysis upper limit method are carried out.The comparison shows that the calculation results of the two methods are relatively close.The python script is compiled and the Abaqus interface is connected to complete the parameter discrete study of the slope soil.Influence of parameter inhomogeneity on slope stability analysis.Finally,taking the actual project as an example,the reliability of the slope of Xingquan Railway Section 440 under normal conditions is calculated.Compared with the target reliability of3.2～ 3.4,the site slope is safe enough under normal conditions.3.The reliability evaluation of the slope of Xingquan Railway Section 440 under rainfall and earthquake is carried out,and a local reliability calculation model of the slope based on the Mohr-Coulomb constitutive model is established.The soil strength reserve is used as the limit state function,and the JC method is used to obtain The calculation results of the local reliability of the slope under different water content and different degrees of variation after rain show that the slope surface is more prone to local damage than the depth of the slope,and the failure probability of the middle and slope angle is up to 22% under saturated water content.and 49%,the failure probability becomes higher under high variation.In order to verify its accuracy,the indoor model slope is filled according to 1:50and sensors such as water content and displacement gauge are buried.Saturated,the slope surface has obvious displacement changes during the rainwater infiltration stage,and the observed phenomenon shows that local damage occurs in the slope angle and slope after 226 minutes of heavy rainfall,which is close to the reliability calculation results,indicating that the results are close to reality.4.Using the combination of the response surface method and the Monte Carlo method,the failure probability under the horizontal seismic acceleration of 0.1g～0.8g increased from28.5% to 51.7%;the reliability decreased from 0.56 to 0,indicating the reliability of the slope with the greater the earthquake magnitude.The lower the degree is,compared with the relevant specifications,the reliability of the on-site slope is safe at 0.4g(level 9 fortification intensity).The time attribute of earthquakes is not negligible.The yield acceleration of the on-site slope was analyzed by the time history method,and the time history curve of the safety factor under different magnitudes was obtained.The random field function of Optum G2 was used to calculate the slope moisture content variability The slope yield acceleration distribution type is log-normal distribution.The Monte Carlo method is used to calculate the failure probability time history curve of the slope under different magnitudes of EL/sine wave.The seismic energy is proportional to the failure probability,and the average failure rate of the EL wave under different magnitudes The probability increased from 0.2%to 17.8%,and the sine wave failure probability increased from 24.1% to 34%.The comparison found that the quasi-static method would overestimate the slope failure probability,and the calculation was more conservative.5.The anti-sliding pile support is actually subjected to force together with the generated soil arch.Based on the Ito plastic flow theory,the reliable performance of the anti-sliding piles under different water contents is studied.The results show that when the soil is close to saturation,Anti-slide pile-soil reliability decreased from 4.6 to 3.8.The influence of pile spacing,pile diameter and spacing ratio on the reliability of anti-sliding piles is analyzed.There is an inflection point in the spacing ratio,and the reliability will drop rapidly when the inflection point is exceeded.Therefore,it is recommended to consider the influence of the spacing ratio against sliding piles for different engineering situations.The limit state method has been recognized as a development trend.When the limit state method is adopted according to the requirements of the code,the internal force of the pile body needs to be less than the ultimate bearing capacity.In this paper,a random reliability calculation program based on the K method is compiled and the reliability is verified by comparing the field test data.The limit state design method is used to redesign the field anti-sliding piles,and the optimal design scheme is screened.The size is 1.75×2.75,which is the same as the result of the allowable stress method.The optimal safety factor of the anti-sliding pile is in the range of 2.0～2.4,indicating that the reserve of 2 times the strength is to meet the engineering needs. |
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