承重夯土墙的改良优化

发布时间：2018-08-19 12:08

【摘要】：生土结构房屋是应用历史最久且分布最为广泛的传统建筑形式,具有可就地取材、可降解再生、施工简易、造价低廉、热工性能突出以及低能耗无污染一系列优点,研究承重生土墙的性能对生土结构房屋的设计和建造有着重要意义。本文通过对承重生土墙的文献和实地调研,分析归纳墙体的破坏特征和承载性能,探讨承重墙体抗剪承载力的影响因素,提出承载夯土墙的抗剪承载力计算公式,针对生土材料在力学性能和抗水性的缺陷,采用掺粘土石化剂进行改良优化,并用有限元模拟墙体在水平剪切作用下的力学性能,相关工作及结论如下:1、对四川部分地区的生土房屋墙体进行实地调研,得到了当地村落生土房屋墙体的结构形式、建筑材料、营造技术和质量病害相关的资料。生土墙体的结构形式有土坯墙体和夯土墙体。夯土墙在建筑材料方面采用粘性土以及掺有沙、碎石、石屑的土两种,墙体的营造技术有椽筑法和版筑法,其质量病害主要体现在地基不均匀沉降和基础的处理不当引起的破坏、墙体受压承载力不足引起的破坏、构造措施不当引起的墙体破坏、结构体系不规则引起的破坏、自然因素引起的墙体破坏、长期使用引起的墙体破坏的方面。2、分析竖向压力、高宽比、夯土材料对于生土房屋墙体的抗剪承载力的影响,由夯土墙体剪切破坏模式符合剪摩理论,建立承重夯土墙抗剪承载力计算公式,并从材料的选择、墙体尺寸的选择、构造措施和施工工艺四个方面提出抗震措施建议。通过分析得到随着竖向压力的增大,墙体的抗剪承载力提高,但竖向压力过大会出现以受压破坏为主的剪压破坏;高宽比较小时,提高了墙体的抗剪承载力和稳定性,高宽比较大时,墙体的抗剪承载力低,容易出现侧向倾斜坍塌;含水率变化越大,墙体产生的干缩裂缝越多,对其抗剪强度的削弱越明显;夯土材料的粘聚力和内摩擦角的增大,可以提高墙体的抗剪承载力。3、通过在不同生土材料外掺粘土石化剂,研究粘土石化剂对生土的压实功能、抗剪强度和抗水性能的效果,并对含粘土石化剂的夯土墙体抗剪承载力建模,最后模拟抗剪试验,验证模拟的准确性。试验表明随着粘土石化剂掺量的增加,土体的最大干密度增大,最优含水率降低,抗剪强度和抗水性相应得到提高,黄土的效果优于红土,数值模拟显示结果与实际试验值的误差不超过10%,验证了模拟的正确性。4、通过有限元模拟在不同粘土石化剂掺量下和不同土样的承重夯土墙受竖向荷载和水平剪切作用下的情况,研究墙体的力学性能和受荷变形。模拟发现掺粘土石化剂的墙体的抗剪强度高于素土墙体,且粘土石化剂对黄土墙体的抗剪强度提高效果优于红土墙体,对于墙体受荷变形,粘土石化剂有明显的提高效果,黄土墙体优于红土墙体。
[Abstract]:The building with raw soil structure is a traditional architectural form with the longest application history and the most extensive distribution. It has a series of advantages such as local material, biodegradable regeneration, easy construction, low cost, outstanding thermal performance and low energy consumption and no pollution. It is of great significance to study the performance of the soil wall for the design and construction of the building with raw soil structure. Based on the literature and field investigation, this paper analyzes the failure characteristics and bearing capacity of the wall, discusses the influencing factors of the shear bearing capacity of the bearing wall, and puts forward the formula for calculating the shear bearing capacity of the bearing rammed earth wall. Aiming at the defects of mechanical properties and water resistance of raw soil materials, the mechanical properties of wall under horizontal shear were simulated by finite element method. The related work and conclusion are as follows: 1. Through the field investigation of the raw soil house wall in some parts of Sichuan province, the structure form, building material, construction technology and quality disease related data of the local village raw soil house wall are obtained. The structure form of raw soil wall has adobe wall and rammed earth wall. The rammed earth wall uses clay soil and soil mixed with sand, gravel and stone debris in building materials. The building techniques of the wall include rafter building method and plate building method. Its quality diseases are mainly reflected in the failure caused by uneven settlement of foundation and improper treatment of foundation, the failure caused by insufficient bearing capacity of wall under compression, the failure of wall caused by improper construction measures, and the damage caused by irregular structure system. Analysis of the influence of vertical pressure, aspect of wall damage caused by long-term use, ratio of vertical pressure, aspect of height to width and rammed earth material on shear capacity of raw soil house wall, According to the shear failure mode of rammed earth wall in accordance with the shear friction theory, a formula for calculating the shear bearing capacity of loadbearing rammed earth wall is established, and suggestions for seismic measures are put forward from four aspects: selection of materials, selection of wall size, construction measures and construction technology. The results show that the shear bearing capacity of the wall increases with the increase of vertical pressure, but the shear-compression failure is mainly caused by the compression failure when the vertical pressure is too high, and the shear bearing capacity and stability of the wall are improved when the ratio of height to width is small. When the height and width of the wall are large, the shear capacity of the wall is low, and the lateral inclined collapse is easy to occur, and the larger the change of moisture content, the more the dry shrinkage crack of the wall, and the more obvious the weakening of the shear strength of the wall. The increase of cohesive force and internal friction angle of rammed soil material can improve the shear bearing capacity of wall. By adding clay petrochemical agent into different raw soil materials, the compaction function, shear strength and water resistance of clay petrochemical agent to raw soil are studied. The shear bearing capacity of rammed earth wall with clay petrochemical agent was modeled and the shear resistance test was simulated to verify the accuracy of the simulation. The test results show that the maximum dry density of soil increases, the optimum moisture content decreases, the shear strength and water resistance increase with the increase of the amount of clay and petrochemical agent, and the effect of loess is better than that of red soil. The error between the numerical simulation results and the actual test value is not more than 10, which verifies the correctness of the simulation. The finite element method is used to simulate the vertical load and horizontal shear action of the rammed soil wall under different clay and petrochemical additives and different soil samples. The mechanical properties and loading deformation of the wall are studied. It is found that the shear strength of the wall mixed with clay petrochemical agent is higher than that of the plain soil wall, and the shear strength of the loess wall is better than that of the clay wall. Loess wall is superior to laterite wall.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU361

【参考文献】