不同非均质系数对土体注浆压裂过程影响的数值模拟研究

Numerical simulation of the influences of different heterogeneity coefficients on the soil grouting fracturing processes

摘要

软弱黏土地基容易产生不均匀沉降，威胁水工建筑物安全。黏土固结注浆是改善其力学性质的有效手段，但是传统有限单元法及离散单元法在处理黏土注浆劈裂过程存在局限。为探究黏土注浆开裂机制，建立一套可以模拟土体注浆劈裂浆脉发展过程的无网格数值方法，在SPH框架下定义了“土体粒子”与“浆液粒子”,推导了注浆压力下“浆液粒子”与“土体粒子”的相互作用方式，引入了一个可以反映粒子失效的断裂标记κ,可以模拟土体注浆劈裂裂缝渐进扩展形态。考虑土体的非均质特性，引入Weibull分布函数考虑抗拉强度的非均匀分布，对不同非均质特性下的土体注浆劈裂特性进行了数值模拟，结果显示：所提出的改进SPH方法可以很好的模拟黏土注浆劈裂过程中的浆脉发展过程。结果表明：不考虑土体非均质性时，浆脉延伸形态单一且对称，而考虑土体非均质性时，土体注浆压裂形态较为复杂，形成纵横交错的浆脉网络。在浆脉起裂前，注浆形成的土体扰动主要集中于注浆孔附近，而在浆脉起裂后，浆脉沿线土体均受到较大的扰动。最后，讨论了土体注浆压裂裂缝形成机制，发现土体注浆压裂分叉形态是由土体非均质特性导致的，并对SPH在土体注浆压裂模拟中的应用前景进行了展望，未来研究应着眼于开发三维高性能并行SPH算法。

Abstract

Soft clay foundation is easy to produce uneven settlement, which threatens the safety of hydraulic structures. Clay consolidation grouting is an effective means to improve its mechanical properties, but the traditional finite element method and discrete element method have limitations in dealing with the splitting process of clay grouting. In order to investigate the cracking mechanism of clay grouting, a meshless numerical method was established to simulate the development process of soil grouting splitting veins, in the SPH framework, the “soil particles” and “slurry particles” are defined, and the interaction between “slurry particles” and “soil particles” under grouting pressure is deduced. A fracture marker κ, which can reflect the failure of particles, is introduced, which can simulate the progressive expansion of soil grouting splitting cracks. Considering the heterogeneous characteristics of soil, Weibull distribution function is introduced to consider the heterogeneous distribution of tensile strength, and the soil grouting splitting characteristics under different heterogeneous characteristics are numerically simulated. The result show that the improved SPH method can well simulate the development process of slurry veins during clay grouting splitting. The above implementation fully demonstrates that: When the soil heterogeneity is not considered, the extension shape of slurry veins is single and symmetrical, while when the soil heterogeneity is considered, the soil grouting fracturing shape is more complex, forming a criss-cross network of slurry veins. The soil disturbance caused by grouting is mainly concentrated in the vicinity of the grouting hole before the grouting pulse cracking, but after the grouting pulse cracking, the soil along the grouting pulse is greatly disturbed. Finally, the formation mechanism of soil grouting fracturing fracture is discussed. It is found that soil grouting fracturing bifurcation is caused by soil heterogeneous characteristics, and the application prospect of SPH in soil grouting fracturing simulation is prospected. Future research should focus on the development of 3D high-performance parallel SPH algorithm.

关键词

断裂标记 / 土体注浆压裂 / 裂缝形态 / 非均匀分布 / 数值模拟

Key words

fracture marker / soil grouting fracturing / fracture morphology / non-uniform distribution / numerical simulation

基金资助

国家自然科学基金项目“冻融与冰推共同作用下土石坝护坡破坏机理及数值模拟方法研究”(51979173)