夯土劣化机理及其对福建土楼力学性能影响的研究

The world cultural heritage -- Fujian earth building is an important part in our country building civilization, is known as "A shinning pearl of the Oriental civilization ". But hundreds of years of natural disasters, climate environment and human factors, resulting in varying degrees of damage, the main disease in active earth building to see, because of climate change, leading to rammed earth material performance degradation, greatly reduce the safety and durability of buildings, has become the most direct and the protection of buildings is the most urgent problem. This project uses the spot test, numerical simulation, model test and theoretical analysis, proved the rammed earth degradation factors, mechanism and regularity, research the rammed earth degradation time-varying model and degrade damage constitutive relationship, and puts forward the degradation disease in rammed earth wall of integral structure resistance calculation model and methods, combined with the actual active earth buildings, to establish the rammed buildings with rammed earth degradation reliability evaluation standard, to determine the bearing capacity of deterioration of the disease in the limit. On this basis, the application of project results on the world's cultural heritage earth building, to assess the safety level of deterioration of the disease in rammed earth structure and puts forward the measures for protection and restoration of rammed earth buildings degradation, analyzes earth building maintenance reinforcement effect, to ensure the using function of the active earth building. The purpose of this research is to Fujian earth building maintenance reinforcement and provide scientific basis for reasonable development and utilization, as well as provide reference for other earth architecture research.

世界文化遗产--福建土楼是我国建筑文明的重要组成部分，被誉为"东方文明的一颗璀璨明珠"。然而几百年来的自然灾害、气候环境和人为因素等，造成土楼不同程度的损伤和破坏。就现役土楼的主要病害来看，因气候环境变迁，导致夯土材料性能劣化，极大降低了土楼安全性和耐久性，已成为土楼保护最直接和最急迫的问题。本项目采用现场测试、数值模拟、模型试验和理论分析，探明夯土劣化因素、机理及规律，研究夯土劣化时变模型和劣化损伤本构关系，提出劣化病害夯土墙整体结构抗力计算模式和方法，结合现役土楼实际，建立夯土劣化土楼可靠性评价标准，确定劣化病害土楼的极限承载力。在此基础上，将项目成果应用于世界文化遗产土楼，评估劣化病害土楼夯土结构的安全等级，针对性提出土楼夯土劣化保护修复措施，分析土楼维护加固效果，保障现役土楼使用功能。本项目的研究既为福建土楼的维护加固和开发利用提供科学依据，也为其它生土建筑研究提供借鉴及参考。

在福建土楼世界文化遗产所在地龙岩的永定县从非世界文化遗产土楼上割取了二百余个试块，测试了夯土块的盐碱种类和含量，并用含盐重塑夯土块，进行了试块材料的抗压、抗剪等力学试验，测取劣化夯土的抗压、抗剪强度值，经数理统计，导出不同劣化程度的夯土材料的力学指标。 .在夯土劣化状态下，除计算土楼夯土结构可靠性外，还计算分析外部土墙内部木构的土楼整体组合结构的承载性能。项目组在福州大学海峡两岸防灾实验中心进行了缩尺土楼模型的震动台抗震试验，在华侨大学土木工程实验中心进行了缩尺土楼模型的拟静力试验，初步探明了土楼整体组合结构承载性能和土墙木构协同受力机理。.将夯土劣化整体结构的承载能力与未计夯土劣化整体结构的承载能力进行比较分析，以夯土表层平均裂缝深度及宽度来体现夯土劣化程度，提出细、宏观尺度下的夯土劣化速度计算模型，进而提出土楼夯土劣化程度五个等级标准：未劣化损伤、轻度劣化损伤、中度劣化损伤、较重劣化损伤和严重劣化损伤，以合理划分现役土楼的劣化等级，可针对性提出不同的修缮加固措施。.本项目研究重点放在成果应用上，根据福建土楼特点，本项目以永定高北土楼群为例，对该土楼群现场调研测评，“五云楼”南面和东面墙体风雨侵蚀特别严重，南面纠偏处理不到位，将其定为严重劣化损伤，需即时进行加固改造；“四泽楼”南面墙体剥落较为严重，且南面墙体有微倾斜，定为较重劣化损伤，需限时进行加固处理；“承启楼”和“侨福楼”均是墙体裂缝较大，部分墙面剥落，定此二楼为中度劣化损伤，需进行日常维护，定期集中修缮。 .在前期研究成果的基础上，根据不同土楼类别，明确不同保护要求，对世界文化遗产土楼，按照文物保护“修旧如旧”，“不改变文物原状”的原则，提出土楼适应性的裂缝灌浆和墙面喷涂的加固措施和方法，项目组开发出了产生钙化物质的微生物材料，在非世界文化遗产的土楼墙面上进行了现场试验，墙体灌浆现场实体试验也将尽快进行，以期取得实际应用。