Why is loess not easy to seepage? Why loess is not easy to seep water

First of all, the loess is mainly composed of silt particles, and the vertical joints are developed, and its vertical permeability coefficient is actually quite considerable. This is an empirical **.

There are several layers of paleosoil in the natural loess, as well as layers of calcareous nodules, and even layers of calcium plates. I think they are influencing the infiltration of water in the loess.

The physical properties of loess are loose, porous, vertical joints are developed, it is very easy to seep water, and there are many soluble substances, which are easily eroded by flowing water to form valleys, and are also easy to cause subsidence and collapse. The combination between the loess particles is not tight, and the porosity is generally 40 50.

Therefore, loess is susceptible to water seepage.

In the loess engineering community, the advantages and disadvantages of the site are generally measured according to the saturation and water collapse of all or part of the collapsible soil layer of the foundation and the engineering countermeasures are formulated, which is often far from the reality. In fact, most of the loess foundation collapse accidents are related to underground pipe ditch water seepage, pipe ditch and other linear sources of water seepage increase the local water content of loess foundation, and the local soil layer of the foundation reaches different humidification water content along the depth and width direction, and causes uneven humidification collapsible deformation. The reason for the collapse accident of loess foundation is not so much the large amount of collapsibility, but the excessive difference of collapsibility.

To study the problem of humidification and collapsible deformation caused by water seepage in pipe trenches, it is necessary to first determine the changes in the moisture field of loess foundation under pipe and ditch seepage, that is, to determine the humidification range and humidification amplitude of loess foundation, and then further calculate and analyze the humidification and collapsible deformation of loess foundation. There is a lack of research in this area. Based on this, this paper studies the change of loess foundation water field under pipe ditch seepage.

Based on the actual water leakage of the pipe ditch in the project, considering the influence of the initial water content, porosity ratio, water pressure in the pipe ditch and other factors, the finite element calculation model of the infiltration of the two-dimensional unsaturated loess foundation pipe ditch was given, the model parameters were determined, and the software was compiled to calculate and analyze the water field of the loess foundation under the seepage of the pipe ditch. The water pressure in the pipe trench is considered according to the three situations of no pressure, full water and pressure, and the initial water content of the foundation soil is 15% and 20% respectively, and the porosity ratio is taken respectively9 and , the change process of the soil moisture field of homogeneous loess foundation infiltration for 3 years was calculated respectively.

The results show that the larger the soil porosity ratio, the larger the initial water content, the faster the infiltration rate, and the larger the foundation humidification area, but with the increase of the humidification area, the diffusion effect of the infiltration water is enhanced, and the saturated area decreases. The smaller the soil porosity ratio, the smaller the initial water content, the slower the infiltration rate, and the smaller the foundation humidification area, which shows that the low saturated dense soil has a strong water blocking effect, and the water is difficult to infiltrate, mainly concentrated around the pipe ditch, the water diffusion effect is weak, and the saturated area is larger. With the increase of time, the range of infiltration and humidification increases.

However, after the ditch water is connected with the groundwater, due to the formation of the infiltration channel, the ditch water can enter the ground faster, and the humidification range is reduced. The pressure of water accumulation in the pipe trench has a great influence on the infiltration of loess foundation, and the greater the pressure, the faster the infiltration and the larger the humidification range.

Loess is porous, vertically jointed, easy to seepage, and has many soluble substances, which are easily eroded by flowing water to form valleys, and are also easy to cause subsidence and collapse. The combination between the loess particles is not tight, and the porosity is generally 40 50.

Therefore, loess is not easy to seepage...

Loess is an acidic soil, the viscosity of the soil is large, the adsorption of water is more, it is easy to be saturated, and a waterproof layer is formed on the surface after saturation.

Personally, I think you should be asking "Why is red clay not easy to seep water?" ”

The particle size of loess is small, the density is large, the viscosity of water increases, and the plasticity increases. Therefore, it is relatively difficult to seep water.

There is no sand and gravel in the loess.

The permeability of loess is relatively strong.

Liu Nanwei, editor-in-chief of South China Normal University, said in "Physical Geography" that one of the characteristics of loess is that the structure is loose and permeable. Porosity is due to the large and large space between the particles. It is easy to get wet after contact with water.

The loess in the Loess Plateau region has good upright properties and is not easy to collapse. There were heavy rains in July and August.

But the rainstorm comes and falls much faster, and it can go back quickly, as long as there are potholes on the top and around the cave, it is not easy to accumulate water, and the loess is not easy to be soaked by seepage, and it is not easy to collapse. If the loess is soaked, it will collapse quickly.

This is the characteristic of loess, which is impermeable.

The uniqueness of the soil quality of the Loess Plateau, uprightness.

1.In view of the geographical area through which the Yellow River flows and the local climatic conditions, tell us how the Yellow River turned yellow, and how do we manage the Yellow River?

A: The reason why the Yellow River turns yellow is because of soil erosion caused by the soil of the Loess Plateau and the excessive reclamation of land by people. The protection of the environment and afforestation should be strengthened.

2.How is the loess of the Loess Plateau formed?

A: The Loess Plateau was formed by flooding, loess sedimentation and neotectonic uplift brought about by the Himalayas.

3.Why don't the caves in the Loess Plateau collapse?

Answer: Because loess has uprightness. It is easy to collapse when flooded, but the Loess Plateau does not have much precipitation, and the loess is not easy to seep.

4. What are the coal fields on the Loess Plateau?

Answer: There are Shenfu, Juye, Shenhua, Qinshui, and Huaibei.

Cave because the loess is upright. It is easy to collapse during flooding, but the Loess Plateau does not have much precipitation, and the loess is not easy to seep water (long-distance land).

Cliff cave (cliff kiln).

The cliff type cave has the mountain type and the ditch type, and the cave often presents a curved or broken line arrangement, which has a harmonious and beautiful architectural art effect. When the height of the hillside allows, several tiers of terraced caves are sometimes arranged, similar to buildings.

Sunken kiln (underground kiln).

Sunken caves are underground caves, mainly distributed in the loess plateau area - areas where there are no hillsides and ditch walls to use. The practice of this kind of cave is: first dig a square pit on the spot, and then go to the four walls of the cave to form a courtyard.

When people are on flat ground, they can only see the treetops of the courtyard, but not the houses.

Free-standing kiln cave (hoop kiln).

The free-standing cave is a kind of vaulted house that covers the earth, and there are adobe arch caves, as well as brick arch stone arch caves. This kind of cave does not need to rely on the mountain and cliff, can be independent on its own, and does not lose the advantages of the cave. It can be a single storey or a building.

If the upper layer is also a hoop kiln, it is called "kiln on kiln"; If the upper floor is a wooden house, it is called a "kiln house".

In a nutshell: because of the different soil qualities, the viscosity is larger, and the Loess Plateau itself rarely rains.

The loess in the Loess Plateau region has good uprightness.

The cave also collapsed, and the cave that did not inhabit people collapsed after a while.

The loess in the Loess Plateau region has good uprightness, so it is not easy to collapse.

The stickiness of the soil is particularly good, unlike ordinary places, I don't know if you are in **, you may not have seen the soil there, I worked again, my students can make models with soil and mud, they will not fall off, they are particularly hard, and they can break the foot bones if they fall to the feet!

Because of the different soil quality, the viscosity is large, and the Loess Plateau itself rarely rains.

Cave because the loess is upright. It is easy to collapse during flooding, but the Loess Plateau does not have much precipitation, and the loess is not easy to seep water (long-distance land).

Rice cultivation requires a large amount of water, and the evaporation is vigorous in the Ailao Mountain River Dam area, and the water vapor rises layer by layer with the hot air mass, and cools and condenses into dense fog and abundant precipitation when it encounters a cold air mass in the high mountainous area.

Due to the vertical change of vegetation, Ailao Mountain forms a large area of alpine forest, which not only has the role of maintaining water and soil, but also has a huge water storage effect, as well as a strong transpiration effect. There are countless springs, streams, waterfalls, pools, and rivers in the forest. There are 29 tributaries in the water system dominated by the two main streams of the Yuanjiang River and the Tengtiao River, with a total water resource of 100 million cubic meters and a usable water resource of 100 million cubic meters, which is the total source of all water sources and the lifeblood of terraced rice farming.

TopographyYunnan has 94 of the area of mountains, the core area of Yuanyang County is 100 of the land is the mountains and mountains, here for hundreds of millions of years by the Yuanjiang River, the rattan river water system depth cut, the central bulge on both sides of the low, the mountains are continuous, the terrain is V-shaped development, not easy to cultivate. In order to produce food, the local terrain had to be transformed, which was an important foundation for the formation of the Hani terraces.

On the slopes of the mountains where the Hani people live, above each village, there are dense forests, providing water conservancy, timber and charcoal, and thousands of terraced fields below the village produce food; The village is composed of mushroom-shaped cottages to form a place to live in peace; Coupled with the alpine natural green reservoir formed by transpiration of rivers and forest storage, it has been praised by cultural ecologists as a virtuous cycle ecosystem with a high degree of harmony and sustainable development between man and nature that is isomorphic to the four degrees of "rivers, forests, villages, and terraces".

In such a mountainous area with a large slope, if there is no good soil and water conservation, the cultivated fields will be wasted. The Hani people take the tree as the guardian god, and subdivide the forest into the sacred forest, the village forest, and the water source forest, which are never allowed to be destroyed, and once someone violates the rules, the punishment is severe. For centuries, the Hani people have carefully guarded their system of "forest, water, and terraces".

In terms of irrigation, there is also a set of strict and effective water use system, from digging ditches and digging ditches, labor input, to ditch ownership, water allocation, ditch management and maintenance, etc., all of which are carefully managed.

The most important thing besides water is fertilizer, and the Hani people took advantage of the geographical advantages of the village on the top and the terraced fields on the bottom, and invented the "flushing fertilizer method". Each village has dug one to several public manure ponds, the manure and sewage of cattle, horses and livestock are stored in it, and over the years, it is black and smelly, and becomes efficient farm fertilizer, and the pond mouth is dug in the spring ploughing season, and water is released from the big ditch to wash it into the field. Therefore, it has maintained the integrity of the natural ecology of Ailao landscape, soil, fertilizer and field, and in today's view, it can be called a model of ecological agriculture.

Because the loess is cohesive, so after the rain, the cave did not collapse, and the precipitation on the Loess Plateau is too little, when it rains, it only washes away the surface layer of loess, and the deep loess is still dry and hard.

The loess alone is indeed afraid of water, but the cave is not a separate loess, it is accumulated little by little by a little through particularly compact loess, and then the cave made has encountered water in the production process, and the effect of making it is also very good, so the cave will not collapse easily.

This is related to the amount of rain, if the rain is small, because the clay of the cave loess is relatively large, and it will be well drained and it is not easy to accumulate water, so it is not so easy to collapse.