深厚表土地层人工多圈管冻结方案优化及冻胀力控制研究

Currently, the new built mine represented in Huainan and Huaibei region through the thickness of the surface soil is increasing, In order to ensure the smooth progress of the wellbore dig puzzle, the mine built mostly used three or even four cycles freezing pipes to increase the frozen wall’s thickness to resistant the huge pressure. But the soil’s basic frost heave characteristics in the multi-circle pipes freezing process of the deep stratum are still not fully grasped at home and abroad, therefore the further expansion of the relevant basic research is required.The study proposed deep soil frozen soil frost heaving force (rate) test under conditions close to the actual boundary engineering, to grasp the frost heaving features of deep overburden strata, Build the constitutive model of frozen soil frost heave. Proceed multi-tupe freezing model test under different pipe arrangement, through water, heat, force three field variables testing and analysis, build a calculation model of frozen wall water-freeze-thermal coupling. Combined heave test and model test, proposed multi-tupe freezing wall calculation method and optimization design. With numerical software, Import the calculation model for finite element program second development, supplemented by a large number of examples to validate the field engineering, to effectively forecast the frost heaving force development state, proposed the method of frost heaving force controlling internal the frozen wall. This research project is the foundation of deep frozen wall mechanical calculation, has important theoretical and practical significance for deep freeze wall and the wall structure design.

以两淮地区为代表的新建矿井穿越表土层厚度不断加大，为保证井筒掘砌的顺利进行，工程上普遍采用三圈甚至四圈管冻结来增加冻结壁的厚度以抵抗较大的地压，而当前国内外对多圈管冻结过程冻结壁力学特性掌握尚不够全面，需进一步开展相关方面基础研究。本研究拟进行接近工程实际边界条件下的深土冻土冻胀力（率）试验，以掌握深厚表土地层土体冻胀特性，构建冻土冻胀本构模型；进行不同冻结管布置方式的多圈管冻结壁模型试验，通过对水、热、力三场变量测试与分析，构建冻结壁水热力耦合计算模型；结合冻胀试验与模型试验结果分析，提出多圈管冻结壁计算方法与优化设计方案；借助数值计算软件，导入计算模型进行有限元程序二次开发，并辅以大量工程现场实例进行验证，对冻胀力发展状态进行有效预测，提出多圈管冻结壁内部冻胀力的控制方法。本项目的研究是深井冻结壁力学计算基础，对深井冻结壁与井壁结构设计具有重要的理论与现实意义。

煤炭开采新建或改扩建冻结井筒中，冻结方案设计是否合理，直接影响到冻结壁的强度与稳定性问题，在多圈管冻结方案的优化设计和冻胀力控制方面仍然需要进一步深入研究。本项目采用室内试验、理论分析、模型试验、数值计算、现场实测等多种分析手段相结合，开展了以下内容研究：.（1）进行了不同影响因素条件下深厚冻土物理力学性能试验，分析获得了冻土强度受土层含水量、含砂率、冻融循环次数、长期荷载等多种因素影响的敏感程度，建立了基于级连相关神经网络的人工冻土本构模型。.（2）研制出一套多功能冻胀试验系统，基于此开展不同外边界条件下人工冻土冻胀试验，获得大荷载、单向冻结、双向冻结等多种更接近工程现场实际冻结工况下冻土冻胀特性。.（3）进行不同冻结方案条件下多圈管冻结模型试验，结合数值计算与现场实测结果，揭示出不同冻结方案以及冻结管偏斜情况对冻结壁交圈时间、井帮温度、冻结壁有效厚度、平均温度等各种特征参数的影响规律。.（4）基于以上试验成果，分析获得多圈管冻结壁温度、水分、应力场发展变化特征，并提出冻结壁内部冻胀力控制措施的建议。.通过本项目的研究，对冻结法凿井过程中，进一步认识多圈管冻结壁的力学性质、深井多圈管冻结方案的优化、冻结壁形成过程中产生的冻胀力控制等方面都具有一定的理论和现实指导意义，同时研究成果对市政工程领域地层冻结加固提供参考。