基于空间挤压效应的软土填筑路基承载特性和固结机理研究

Because the traditional disposal techniques and methods of soft clay filled subgrade are influential to ecology and environment. In this project , based on the spatial squeezing effect , the bearing characteristics and consolidation mechanism of soft clay filled subgrade will be analyzed and discussed with indoor model test , numerical simulation and theoretical calculations. After the soft clay filled subgrade test model will be simplified, the model of soft soil subgrade numerical analysis of particle flow will be established under the condition of the space squeezing function to get soft soil micro parameters and simulate to analysis the inflatable anchor distribution law of roadbed and pneumatic parameters. According to the numerical simulation results, the indoor similar simulation experiment will be carried out, the additional stress distribution law, pore pressure variation condition and physical mechanics parameters variation law of soft clay soil will be revealed, the additional stress function relational with the Cross inflatable bolt pressure model will be established to predict the roadbed consolidation degree. Meanwhile, the circular expansion theory will be introduced to discuss the relationship of the anchor inflatable extrusion process pressure and swelling volume, the stress-strain relationship of the expansion soil around will be revealed, and the limit inflation pressure and the ultimate bearing capacity will be predicted. Finally, based on the principle of minimum potential energy and minimum complementary energy principle, the appropriate displacement function will be selected , the soft clay subgrade bearing capacity formula and improved the formula of foundation settlement will be deduced under the space squeezing function, and calculated results of formula will be compared to the experimental results .

针对软土填筑路基的传统处置技术和方法对生态和环保的影响，本项目拟采用室内模型试验和数值模拟实验相结合，实验研究与理论计算相结合，开展基于空间挤压效应的软土填筑路基承载特性和固结机理研究。通过简化试验软土路基模型，建立空间挤压作用下软土路基颗粒流数值分析模型，获取软土细观参数，模拟分析路基中充气锚杆的分布规律和气压参数；基于数值模拟结果开展室内相似模型试验，揭示路基中不同深度的附加应力分布规律、孔隙压力变化规律和路基物理力学参数变化性状，建立十字充气锚杆气压与软土路基中不同距离的附加应力的函数关系模型，预测路基固结程度；同时引入圆形扩张理论，探讨十字锚杆充气挤压过程中充气压力与膨胀体积关系，揭示膨胀体周围土体的应力应变关系，预测极限充气压力及其极限承载力；最后基于能量法原理，选取适当位移函数，推导空间挤压作用下软土路基的承载力公式和改进的地基沉降公式，并与实验结果相互验证。

本项目在空间挤压效应的软土填筑路基承载特性和固结机理研究的基础上，开展了砂土单囊式充气锚杆循环荷载作用承载特性及其群锚效应研究，研究其在不同充气压力、不同埋置深度的条件下单根锚杆的承载特性，在循环荷载作用下单根锚杆的位移变化情况，以及在相同埋置深度，不同锚杆间距的情况下群锚的承载特性和群锚效应的变化规律；其次继续开展了黏土充气锚杆变形与承载特性及群锚效应试验研究，研究其在黏土中不同的充气压力、不同埋置深度以及不同含水率的条件下单根锚杆的变形及承载特点，在循环荷载作用下单根锚杆的Q-S曲线形态分析和位移变化情况，以及在相同埋置深度，不同锚杆间距的情况下群锚效应的变化规律，在群锚时不同的锚杆布置形式对群锚承载力的影响，并用极限平衡分析法对锚杆的承载力进行了计算；第三，在之前的研究基础上，对充气锚杆的结构进行了改变，研究了串囊式充气锚杆在砂土中不同充气压力、不同埋置深度、不同气囊长度和不同气囊间距的条件下的承载特性，基于最小二乘法对其位移和荷载的关系进行了分析，并对在不同埋深，不同锚杆间距和不同气囊长度条件下的群锚承载力和群锚效应进行了研究，基于圆孔扩张理论对串囊式充气锚杆的承载力进行了计算。