The principle and application method of systemd are applicable to the principle of systemd.

The principle and application method of systemd are applicable to the principle of systemd.

Principle of systemd:

Https://www.linux.com/learn/tutorials/527639-managing-services-on-linux-with-systemd

Http://ktaraghi.blogspot.com/2013/11/what-is-systemd-and-how-it-works-part-1.html

Http://ktaraghi.blogspot.com/2013/12/what-is-systemd-and-how-it-works-part-2.html

 

Usage: https://fedoraproject.org/wiki/Systemd/zh-cn

What are the principles, methods and applicability of the drainage consolidation method?

3. The basic principle of drainage consolidation method is that under the action of additional load on the soft soil foundation, the pore water is gradually discharged, and the void ratio is reduced, resulting in consolidation deformation. In this process, as the excess pore water pressure of the soil gradually dissipate, the effective stress of the soil increases, the shear strength of the Foundation increases accordingly, and the settlement is completed or increased in advance. The drainage consolidation method is mainly composed of two systems: drainage and pressurization. Drainage can take advantage of the Water Permeability of natural soil layer, especially the characteristics of the Multi-sanded Thin Layer in Shanghai, you can also set vertical drainage bodies such as sand wells, bagged sand wells and Plastic Drainage boards. Pressurization mainly involves the ground load method, vacuum preloading method, and well point precipitation method. In order to reinforce the weak Clay, it is reasonable and effective to use the electric seepage drainage well point under certain conditions. (1) Before building a building, the preloading method is used to load the Foundation by means of temporary piles of soil and rock to pre-complete partial or most of the foundation settlement, the bearing capacity of the foundation is increased through consolidation of the foundation soil, and the load is removed before building. The temporary preloading load is generally equivalent to the building load, but in order to reduce the Settlement Caused by secondary consolidation, the preloading load can also be larger than the building load, known as overload preloading. In order to accelerate the consolidation speed of the Foundation by Preloading, it can be used together with sand well method or plastic water drainage method. If the clay layer is thin and the permeability is good, the heap preloading method can also be used separately. It is suitable for Soft Clay Foundations. (2) The Sand Well Method (including Bagged Sand Wells and Plastic Drainage belts) is used to set up a series of sand wells in soft-stick land bases, and sand cushions or trenches are laid on the sand wells, artificially increase soil consolidation drainage channels, shorten drainage distance, thus accelerating consolidation and increasing strength. The sand well method is usually supplemented by heap preloading, which is called the sand well preloading method. It is suitable for weak and viscous soil with low permeability, but not for organic matter sediment such as clay. (3) The sand cushion is laid on the clay layer by vacuum preloading, and then the sand cushion is sealed with a thin film, and the sand cushion and sand well are pumped with a vacuum pump to reduce the groundwater level, at the same time, the foundation consolidation is accelerated under atmospheric pressure. It is suitable for soft soil foundations that can form in the reinforcement area (including those formed after Measures) with stable negative pressure boundary conditions. (4) The vacuum-Heap Combined preloading method can be used together with the heap preloading method when the vacuum preloading fails to meet the required preloading load, the Heap Preloading load and the vacuum preloading load can be combined for calculation. It is suitable for Soft Clay Foundations. (5) The groundwater position reduction method reduces the pore water pressure in the soil by reducing the groundwater level, thus increasing the effective stress and promoting the consolidation of the Foundation. It is applicable to projects where the groundwater level is close to the ground and the excavation depth is not large, especially for saturated powder and fine sand foundations. (6) The Electroosmotic drainage method inserts a metal electrode into the soil and passes through the direct current. Due to the direct current electric field, the water in the soil flows from the anode to the cathode, and then removes the water from the cathode, instead of adding water near the anode, the water in the soil can be gradually ruled out by Electroosmotic effect. In engineering, it is often used to reduce the water content in the viscous soil or reduce the groundwater level to improve the stability of the foundation bearing capacity or slope. It is suitable for Saturated Soft Clay Foundations.

Which types of seismic analysis methods are commonly used? Briefly describe their principles and Applicability

Common analysis methods in China include bottom shear method, vibrating decomposition response spectrum method, and time-range analysis method.
1. bottom shear method
Applicability: For structures with a uniform distribution of weight and stiffness along height, with a height not greater than 40 m and shear deformation (when the height-to-width ratio of a house is less than 4), vibration has the following characteristics; (1) The displacement reaction is dominated by the basic vibration type; (2) the basic vibration type is close to the straight line.
Basic principle: On the basis of the vibrating decomposition response spectrum method, the specific conditions of some buildings are further simplified, and a method for Approximate Calculation of Horizontal Seismic effect is obtained: the multi-degree of freedom system is simplified to a single degree of freedom system, and the overall Seismic Effect of the structure is calculated (that is, the bottom shear force of the structure). Then, it is allocated to each floor based on the inverted triangle principle to calculate the structural internal force.
2. vibrating decomposition response spectrum method
Applicability: construction structures except the bottom shear force method described above.
Basic principle: using the concept of vibration decomposition method, the multi-degree of freedom system is decomposed into several single-degree of freedom system vibration combinations, the seismic effects of various vibration types are calculated based on the Reaction Spectrum Theory of a single degree of freedom system. Finally, the seismic effects calculated by each vibration type are combined according to certain rules to obtain the total seismic response.
3. Time History Analysis
Applicability: the seismic code stipulates that important engineering structures, such as long-span bridges, especially irregular buildings and Class A buildings, the time-history analysis method should be used for supplementary Calculation of high-rise buildings whose height exceeds the prescribed scope.
Basic principle: the time-history analysis method is a dynamic analysis method that directly solves the moving differential equations of a structure. The displacement, velocity, and acceleration dynamic response of each particle with time change can be obtained from time-history analysis, and the time-history change relationship of the internal force of the component can be calculated.

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