發(fā)布時(shí)間：2018-01-18 16:00

  本文關(guān)鍵詞：基于凍土動荷載直剪儀的高溫凍土動力特性研究　出處：《北京交通大學(xué)》2015年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 高溫凍土 動荷載直剪儀 土的動強(qiáng)度 土的動本構(gòu)模型 動剪切模量 阻尼比

【摘要】：我國多年凍土分布十分廣泛,其中大部分都屬于高溫凍土,同時(shí),青藏高原是我國地震活動水平最高、強(qiáng)度最大的區(qū)域。在這一區(qū)域運(yùn)營中的青藏鐵路、青藏公路等一批具有戰(zhàn)略意義的重大項(xiàng)目,受到凍土溫度升高、可能發(fā)生地震等因素的威脅。針對這一情況,研發(fā)測定凍土動力學(xué)參數(shù)的新型儀器,對低圍壓下高溫凍土的動力學(xué)規(guī)律進(jìn)行研究,并給出一定條件下高溫凍土動力學(xué)參數(shù)的經(jīng)驗(yàn)公式。對路基工程抗震設(shè)計(jì)、計(jì)算均有參考價(jià)值,對保障青藏高原上構(gòu)筑物的安全運(yùn)營具有重要意義。 本文以國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃(國家“973”計(jì)劃)“凍土工程構(gòu)筑物服役性能評價(jià)與預(yù)測(No.2012CB026104)'為依托,以青藏高原地區(qū)典型粉質(zhì)粘土為研究對象,在總結(jié)國內(nèi)外研究現(xiàn)狀的基礎(chǔ)上,通過現(xiàn)場調(diào)查取樣、儀器開發(fā)、室內(nèi)試驗(yàn)等手段,研究了低圍壓情況下高溫凍土的動強(qiáng)度、動剪切模量和阻尼比等重要動力學(xué)參數(shù)。試驗(yàn)結(jié)果給出了不同影響因素對高溫凍土動力學(xué)參數(shù)的影響關(guān)系,為高溫凍土地區(qū)構(gòu)筑物抗震設(shè)計(jì)、計(jì)算提供了較為適用的參數(shù),并驗(yàn)證了新型試驗(yàn)儀器的適用性。主要成果有包括以下幾個(gè)方面： (1)在總結(jié)和分析國內(nèi)外研究現(xiàn)狀的基礎(chǔ)上,指出目前研究的不足之處,認(rèn)為低圍壓下高溫凍土的動力學(xué)特性缺乏系統(tǒng)性的研究,并以此為研究的重點(diǎn)。 (2)通過現(xiàn)場實(shí)地調(diào)研,選取典型場地并進(jìn)行監(jiān)測,并開展相關(guān)的室內(nèi)土工試驗(yàn),掌握了土樣的基本土性,為進(jìn)一步研究青藏高原粉質(zhì)粘土的動力學(xué)性質(zhì)打下基礎(chǔ)。 (3)給出了凍土動荷載直剪試驗(yàn)系統(tǒng)各個(gè)組成部分的研制過程及相關(guān)參數(shù)的確定。分別分析了儀器的液壓動力系統(tǒng)、可控溫直剪盒、作動器與工作平臺的拼接等方面的設(shè)計(jì),并通過控溫效果試驗(yàn)和不同情況的動直剪試驗(yàn)初步驗(yàn)證了新型儀器的試驗(yàn)精度和適用性。 (4)根據(jù)土的動強(qiáng)度理論對高溫凍土進(jìn)行了系統(tǒng)的研究。通過一系列不同溫度、圍壓、振動次數(shù)條件下的動三軸、動直剪試驗(yàn),得到了不同條件下土體的動強(qiáng)度參數(shù)。重點(diǎn)分析了溫度和振動次數(shù)對其動強(qiáng)度的影響規(guī)律,并就兩種試驗(yàn)方法及試驗(yàn)結(jié)果的異同點(diǎn)進(jìn)行對比分析。 (5)通過總結(jié)土動力學(xué)本構(gòu)關(guān)系,并結(jié)合動三軸、動直剪兩種試驗(yàn)得到的試驗(yàn)結(jié)果,確定采用Hardin-Drnevich動本構(gòu)模型對試驗(yàn)結(jié)果進(jìn)行研究。系統(tǒng)的分析了溫度、圍壓、振動次數(shù)等因素對動力學(xué)參數(shù)的影響關(guān)系,并對比分析了兩種試驗(yàn)方法在測定動剪切模量、阻尼比時(shí)的異同,進(jìn)一步驗(yàn)證了新型試驗(yàn)儀器的適用性。
[Abstract]:Permafrost is widely distributed in China, most of which belong to high temperature permafrost. At the same time, the Qinghai-Tibet Plateau is the region with the highest seismic activity level and the highest intensity. A number of important projects of strategic significance such as the Qinghai-Tibet Highway are threatened by factors such as the rise of frozen soil temperature and the possibility of earthquakes. In view of this situation, a new instrument for measuring the dynamic parameters of frozen soil has been developed. The dynamic law of high temperature frozen soil under low confining pressure is studied, and the empirical formula of dynamic parameters of high temperature frozen soil under certain conditions is given, which has reference value for seismic design of subgrade engineering. It is of great significance to ensure the safe operation of structures on the Qinghai-Xizang Plateau. This paper is based on the National key basic Research and Development Plan ("973" Plan), "performance Evaluation and Prediction of Frozen soil Engineering structures No. No.2012CB026104'". Taking the typical silty clay in Qinghai-Xizang Plateau as the research object, on the basis of summing up the present research situation at home and abroad, the field investigation and sampling, instrument development and laboratory test were carried out. The dynamic strength, dynamic shear modulus and damping ratio of high temperature frozen soil under low confining pressure are studied. The experimental results show the influence of different factors on the dynamic parameters of high temperature frozen soil. It provides more suitable parameters for seismic design of structures in high-temperature frozen soil area, and verifies the applicability of the new test instrument. The main results include the following aspects: 1) on the basis of summarizing and analyzing the present research situation at home and abroad, the paper points out the deficiency of the present research, and points out that the dynamic characteristics of the high-temperature frozen soil under low confining pressure are lack of systematic research, and this is the emphasis of the research. 2) through the field investigation, the typical site is selected and monitored, and the related indoor geotechnical test is carried out to master the basic soil properties of the soil sample. It lays a foundation for further study on the dynamic properties of silty clay in Qinghai-Xizang Plateau. The development process of each component of the direct shear test system for frozen earth dynamic load and the determination of related parameters are given. The hydraulic power system of the instrument and the controlled temperature direct shear box are analyzed respectively. The design of the joint of actuator and working platform is carried out, and the accuracy and applicability of the new instrument are preliminarily verified by the temperature control effect test and the dynamic direct shear test under different conditions. (4) based on the dynamic strength theory of the soil, a series of dynamic triaxial shear tests under different temperature, confining pressure and vibration times are carried out. The dynamic strength parameters of soil under different conditions are obtained, and the influence of temperature and vibration times on the dynamic strength is analyzed, and the similarities and differences between the two test methods and the test results are compared and analyzed. 5) through summarizing the constitutive relation of soil dynamics, combining the dynamic triaxial test and the dynamic direct shear test, the experimental results are obtained. The Hardin-Drnevich dynamic constitutive model was used to study the experimental results. The influence of temperature, confining pressure and vibration times on the dynamic parameters was systematically analyzed. The similarities and differences of the two test methods in determining the dynamic shear modulus and damping ratio are compared and analyzed, which further verifies the applicability of the new test instrument.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TU445

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