【摘要】：土孔隙中不僅有液相的流動(dòng)，也有氣相的流動(dòng)。非飽和土的土水特性，表征了非飽和土中基質(zhì)吸力以及水、氣滲透性與含水量的相關(guān)關(guān)系，包括土水特征曲線和相對(duì)滲透率曲線。土水特性是解釋非飽和土行為和求解水氣運(yùn)動(dòng)的基本本構(gòu)關(guān)系，是構(gòu)筑非飽和土中各種重要關(guān)系的基礎(chǔ)。傳統(tǒng)測(cè)試土水特性的方法大都未能考慮土孔隙中氣相的作用，而且土水特性三條曲線的測(cè)定往往是分開進(jìn)行的，難以保證三個(gè)本構(gòu)關(guān)系的相容性。 本文基于水氣二相流的基本理論，，開展了非飽和土水特性的測(cè)試?yán)碚摵头椒ǖ难芯�，開展的主要研究如下： 1）基于土中水氣二相流的基本理論，提出一種新的非飽和土水特性測(cè)試方法。測(cè)試方法包含數(shù)值反算部分和測(cè)試試驗(yàn)部分，能反映非飽和土中水、氣相互作用特征，同時(shí)得到土樣的土水特征曲線和水、氣相相對(duì)滲透率曲線，保證了三條本構(gòu)關(guān)系的相容性。 2）發(fā)展了一種水氣二相流耦合求解與區(qū)間逼近相結(jié)合的土水特性反算方法。反算方法找到了合適的水氣二相流解耦路徑和參數(shù)優(yōu)化路徑，能夠結(jié)合特定的土水特性數(shù)學(xué)模型反算得到土樣的非飽和土水特性。編寫了相關(guān)計(jì)算程序，通過干過程和濕過程的模擬，驗(yàn)證了反算程序的正確性、收斂性及數(shù)值穩(wěn)定性。 3）自主設(shè)計(jì)了一個(gè)干濕循環(huán)多步流動(dòng)試驗(yàn)系統(tǒng)。試驗(yàn)系統(tǒng)能夠模擬土樣中水氣耦合運(yùn)動(dòng)，能夠根據(jù)土樣中水流動(dòng)狀態(tài)自動(dòng)施加干濕循環(huán)條件，實(shí)時(shí)采集試樣邊界條件和溢出水總量，為土水特性數(shù)值反算提供了數(shù)據(jù)支撐。 4）驗(yàn)證了測(cè)試方法的正確性和適用性。根據(jù)實(shí)時(shí)采集試樣溢出水流量和邊界條件、初始條件，結(jié)合相應(yīng)的數(shù)值反算程序，同時(shí)得到了試樣非飽和土水特征曲線和水、氣相相對(duì)滲透率函數(shù)曲線。將測(cè)試所得的非飽和土水特性作為已知條件，進(jìn)行水氣二相流耦合求解，對(duì)比分析計(jì)算的溢出水量與試驗(yàn)采集溢出水量以及水分運(yùn)移規(guī)律，驗(yàn)證了測(cè)試方法的正確性。
[Abstract]:There is not only liquid flow in soil pores, but also gas phase flow. The soil-water properties of unsaturated soils are characterized by the relationship between the matrix suction, water and gas permeability and water content, including soil water characteristic curve and relative permeability curve. The soil-water characteristic is the basic constitutive relation to explain the behavior of unsaturated soil and to solve the water vapor motion. It is the foundation of constructing various important relations in unsaturated soil. Most of the traditional methods for measuring soil-water properties fail to consider the effect of gas phase in soil pores, and the determination of three curves of soil-water characteristics is often carried out separately, so it is difficult to ensure the compatibility of the three constitutive relations. Based on the basic theory of water and gas two-phase flow, the testing theory and method of unsaturated soil-water characteristics are studied in this paper. The main research results are as follows: 1) based on the basic theory of water-gas two-phase flow in soil, A new testing method for unsaturated soil and water characteristics is presented. The test method includes numerical backcalculation part and test section, which can reflect the interaction characteristics of water and gas in unsaturated soil. At the same time, the soil-water characteristic curve and the relative permeability curve of water and gas phase of soil sample are obtained. The compatibility of the three constitutive relations is guaranteed. 2) an inverse calculation method of soil and water characteristics is developed, which combines the coupling solution of water and gas two-phase flow with interval approximation. An appropriate decoupling path and parameter optimization path are found by the inverse calculation method, and the unsaturated soil-water characteristics of soil samples can be obtained by combining with a specific mathematical model of soil-water characteristics. Through the simulation of dry and wet processes, the correctness, convergence and numerical stability of the inverse program are verified. 3) A dry and wet cycle multi-step flow test system is designed. The test system can simulate the coupled motion of water and air in soil sample, can automatically apply dry and wet circulation conditions according to the flow state of water in soil sample, and collect the sample boundary condition and the total amount of overflow water in real time, which provides the data support for the numerical inverse calculation of soil water characteristics. 4) the correctness and applicability of the test method are verified. According to the overflow water flow and boundary conditions, initial conditions and the corresponding numerical inverse calculation program, the characteristic curves of unsaturated soil and the relative permeability function curves of water and gas phase are obtained at the same time. Taking the unsaturated soil-water characteristic of the test as the known condition, the coupling solution of water-gas two-phase flow is carried out, and the correctness of the test method is verified by comparing the calculated overflow water with the experimental collected overflow water and the water migration law.
【學(xué)位授予單位】：三峽大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU411

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