| The soil moisture measuring is the subject which has huge potential and extensive useness. It is often used in the agriculture and industry. The study of the pore water pressure is a relatively younger subject which is more related with agriculture and geological disaster. The soil moisture and the pore water pressure have some common ground. But they are quite different on almost all aspects. The paper first introduce several methods which is often used in measuring soil moisture and pore water pressure and analyze their strongpoint and fault. On the basis of this, the paper introduce a new style of pore water pressure monitoring system which made by Institute of Hydrogeology and Engineering geology Techniques, CGS. The system is studied for the purpose of monitoring coast, but it can also be used in the agriculture.The monitoring system includes the multi-sensor, the field instrument,the communication cable,the controlling software and the data managing software. The field instrument consistsof measuring circuit, data memory, automatic controlling and communication interface. The controlling software includes the field instrument's self-control software and the communication protocol. The ceramic pressure sensor is the key components. It is the innovation of the system. The pressure sensor is the important component of the sensor. In order to search for the mos fitting pressure sensor for the performance and price,we worked for a long time to compare the sensors made by domestic institute of aviation and the American IC company.At last we decided to apply the product of the IC company. The ceramic crust which is studied by ourselves is the key component of the sensor. The theory of ceramic pressure sensor is: after the ceramic crust was soaked, it forms a flat of water film during the pores. The water can go through the film, but the air cann't go through it under some pressure difference. That is inside the ceramic sensor is vacuum. We observed the suction of the sealed ceramic canister which is full of water to the soil. The suction is equal to the negative pressure inside the canister. The pore of the ceramic crust is more small, the measuring range is more wide. But its infiltration get worse. The reflection is slow. The time to get a stable stateis long. We spend a great deal time on experiment. In the end, the most negative pressure of the ceramic pressure sensor is -80Kpa. The data coming from instrument may be negative or positive. The positive data is the water level of the saturated soil from thesensor to the surface .If the data is negative, they show the soil is not saturated. Because the mathematic relates to the soil's construction and the size of the grains, the relation between the negative pore water pressure and the aquiferous rate of soil hasn't a conclusion internationally. Through studing the data receiving from the systeml and the data of soil acquiferous rate receiving from lab, we conclude a arithmetic on the base of former achievement. The arithmetic is fit for the soil whose grains is 0.1-0.2MM and the construction of soil is loose. The type of soil simulate the Three Gorge area's soil. Based on the arithmetic, we program a set of soft. The soft is used on the monitoring of Three Gorge's geological disaster and get a good result. At last the paper introduces the soft's flow chart and how to realize.
|
PDF Full Text Request