CAJ | 학술논문

介绍基于数字图像处理建立数值模型的基本过程,实现由现场数字照片直接生成土石混合体的颗粒流模型.以溪洛渡水电站坝址附近某滑坡土石混合体为例,基于实拍照片建立其细观数值模型,利用 PFC2D程序分析碎石和土体数值模型中微观力学参数的反算问题,分别为滑坡体中的碎石和土体选定与其宏观力学特征相一致的微观力学参数,进行直剪试验的数值模拟,并与均质土体的模拟结果相比较.结果显示:利用双轴试验反算的土体微观参数运用于直剪试验获得的宏观力学参数与实际一致;一定含量的碎石使土石混合体的初始剪切刚度较均质土有所增大,达到峰值抗剪强度所需的剪切位移减少;假定土石界面的黏结强度为土体内部的1/10时,土石混合体的内摩擦角明显增大,而黏聚力则稍有减少;与均质土体直剪形成的破裂面相比,土石混合体模型中的裂隙部分集中于剪切面呈宽带状,部分存在碎石与土体分界面,基于此可定性探讨一定碎石含量的土石混合体抗剪性能优于均质土体的原因.
개소기우수자도상처리건립수치모형적기본과정,실현유현장수자조편직접생성토석혼합체적과립류모형.이계락도수전참패지부근모활파토석혼합체위례,기우실박조편건립기세관수치모형,이용 PFC2D정서분석쇄석화토체수치모형중미관역학삼수적반산문제,분별위활파체중적쇄석화토체선정여기굉관역학특정상일치적미관역학삼수,진행직전시험적수치모의,병여균질토체적모의결과상비교.결과현시:이용쌍축시험반산적토체미관삼수운용우직전시험획득적굉관역학삼수여실제일치;일정함량적쇄석사토석혼합체적초시전절강도교균질토유소증대,체도봉치항전강도소수적전절위이감소;가정토석계면적점결강도위토체내부적1/10시,토석혼합체적내마찰각명현증대,이점취력칙초유감소;여균질토체직전형성적파렬면상비,토석혼합체모형중적렬극부분집중우전절면정관대상,부분존재쇄석여토체분계면,기우차가정성탐토일정쇄석함량적토석혼합체항전성능우우균질토체적원인.
The elementary process of establishing numerical model based on digital image processing is introduced. According to the method,the particle flow numerical models of soil and rock mixture(SRM) can be obtained directly by field digital photos. Taking SRM in a landslide near the dam of Xiluodu hydropower station for example,the numerical model is established by field photo. The micro-mechanical parameters of gravel and soil are well studied by using the particle flow code in two dimensions(PFC2D);and micro-mechanical parameters corresponding to their macro-mechanical features are selected. The numerical simulation of direct shear test for the SRM is conducted under serious normal pressures and the results of SRM are compared with those of heterogeneous soil. The main research results can be summarized as follows:Firstly,the microparameters of soil inversely calculated by biaxial compression test is used in direct shear test to get macroparameters of soil;and these macroparameters are consistent with practice. Compared with heterogeneous soil,the initial shear stiffness of the SRM with certain content gravel is higher,and the shear displacement required for the SRM reaching to its peak shear strength is reduced. Under the assumption that the bonded strength between gravel and soil is one tenth of the soil?s,the internal friction angle of the SRM is larger,while the cohesion is lower. Compared with the fracture plane in heterogeneous soil model after direct shear tests,the cracks developed in the SRM numerical model can be divided into two parts:some are around the shear plane formed broad fractures band,the others distribute between gravel and soil. Also according to the characters of shear failure,the reason for enhancing shear performance of the SRM which contains a certain amount of gravel can be introduced qualitatively.