High-rise Building Group Research Articles

Green technology of water system of high-rise building based on scientific sustainable environment development

In the optimisation design of the water system of a high-rise residential building group, the BIM technology is applied in the green building design framework, the technical measures based on local conditions are adopted, and the economic analysis of the value engineering theory is used to propose the optimisation design technology of the water system of the high-rise residential building group. The framework provides the necessary technical support for the design of a sustainable high-rise residential building water system.

Site-Specific Unmodeled Error Mitigation for GNSS Positioning in Urban Environments Using a Real-Time Adaptive Weighting Model

In Global Navigation Satellite System (GNSS) positioning, observation precisions are frequently impacted by the site-specific unmodeled errors, especially for the code observations that are widely used by smart phones and vehicles in urban environments. The site-specific unmodeled errors mainly refer to the multipath and other space loss caused by the signal propagation (e.g., non-line-of-sight reception). As usual, the observation precisions are estimated by the weighting function in a stochastic model. Only once the realistic weighting function is applied can we obtain the precise positioning results. Unfortunately, the existing weighting schemes do not fully take these site-specific unmodeled effects into account. Specifically, the traditional weighting models indirectly and partly reflect, or even simply ignore, these unmodeled effects. In this paper, we propose a real-time adaptive weighting model to mitigate the site-specific unmodeled errors of code observations. This unmodeled-error-weighted model takes full advantages of satellite elevation angle and carrier-to-noise power density ratio (C/N0). In detail, elevation is taken as a fundamental part of the proposed model, then C/N0 is applied to estimate the precision of site-specific unmodeled errors. The principle of the second part is that the measured C/N0 will deviate from the nominal values when the signal distortions are severe. Specifically, the template functions of C/N0 and its precision, which can estimate the nominal values, are applied to adaptively adjust the precision of site-specific unmodeled errors. The proposed method is tested in single-point positioning (SPP) and code real-time differenced (RTD) positioning by static and kinematic datasets. Results indicate that the adaptive model is superior to the equal-weight, elevation and C/N0 models. Compared with these traditional approaches, the accuracy of SPP and RTD solutions are improved by 35.1% and 17.6% on average in the dense high-rise building group, as well as 11.4% and 11.9% on average in the urban-forested area. This demonstrates the benefit to code-based positioning brought by a real-time adaptive weighting model as it can mitigate the impacts of site-specific unmodeled errors and improve the positioning accuracy.

Model test study on the subsidence of high-rise building group due to variation of groundwater level

With the rapid urbanization, more and more attention has been paid to land subsidence, especially induced by the coupling effect of high-rise building groups and variation of groundwater level in soft soil areas. A model test of the subsidence of a high-rise building group undergoing the groundwater withdrawal and the recharge from different aquifers was conducted and discussed in this paper. The particle image velocimetry technology was used to analyze the long-term deformation of each soil layer, and the results were in good agreement with those measured by LVDTs. The exploitation of groundwater from the deeper aquifer was a good way to control the settlement to some extent, but the subsidence cannot be avoided completely. During the dewatering, the settlement of the soil layer was out of phase with that of the pile foundation, so the negative friction appeared along the pile and the soil settlement was hindered. The compression of two aquitards was the main reason for land subsidence, which was attributed to the decrease in pore water pressure at first following expansion of unsaturated area and the occurrence of high matric suction afterward, as well as the high compressibility of silty clay. The land subsidence caused by the variation of groundwater level was irreversible, and the behavior of water recharge and exploitation in the multilayer soils was not elastic. However, the groundwater recharge had a significant effect on restraining the settlement rate.

High-rise Building Group Regional Fire Risk Assessment Model Based on AHP

Based on Analytic Hierarchy Process (AHP), a regional fire risk assessment model is developed for high-rise building group considering the fire danger degree, basic characters of the high-rise building group and fire control capability. The impact factors, values of typical risk parameter and the weight of each index are analyzed. An assessment program is further developed using Matlab, to perform the risk assessment procedures. The model is then applied to the regional fire risk evaluation of a high-rise building group.

Soil-High-Rise Building Group Dynamic Interaction Considering Site Effect

This article reports a sub-domain method to analyze the dynamic interaction of soil-high-rise building group considering sit effect, which is the extension of the domain reduction method proposed by Bielak and his coworkers in the framework of the finite-element method, originally for building–soil–foundation interaction problems. The whole domain with high-rise building group is divided into two interrelated sub-domains, the external domain and the internal one. And the method contains two steps. In addition, the effect of the external domain to the internal domain is expressed by the equivalent forces which are put on the nodes of the interface between the two sub-domains in the second step. The formation of the equivalent force is attained according to the equation of motion. In the first step the free-field ground motion is calculated under the bedrock wave excitation, and all the nodal displacements are stored. Then the equivalent forces are calculated according the data in the first step, using the formulation of the equivalent force. In the second step a finite element analysis model of the sub-domain containing the internal domain and the high-rise building group is established, and the equivalent forces are put on the nodes of the interface. Later the seismic response of soil-high-rise building group can be calculated.

Application of geo-environmental capacity of ground buildings in urban planning

The restrictions of the geo-environment are often ignored in urban planning, thereby directly causing a variety of geological hazards, including large areas of land subsidence in soft soil area. Based on the control objective of land subsidence, the geo-environmental capacity of ground buildings (GECGB) is defined. The relationship between floor area ratio (FAR) and land subsidence in Shanghai, China is analyzed. The results illustrate that land subsidence increases as FAR increases, and that the engineering environmental effect of the high-rise building group is the main factor affecting land subsidence in Shanghai, China. Hayashi’s Quantification Theory type I is selected to evaluate the GECGB of four typical areas in Shanghai. The prediction model is established based on existing background materials and the GECGB expressed by allowable FAR of the four typical areas are calculated. The evaluation approach promoted in this paper can be applied in urban planning to control the land subsidence induced by dense high-rise buildings.

Numerical Simulation of Land Subsidence Caused by High-Rise Building, Applied in Tanggu, China

Ground subsidence is aggravated and becomes a prominent phenomenon recently in Tanggu, China. The subsidence reached its most critic state because of intensive water over-extraction in 1980s. Thereafter, over-draft withdraw of groundwater has been strictly controlled. Consequently, the rate of settlement decreased in the subsequent period. However, in recent year, ground subsidence becomes a prominent hazard again in some high-rise building areas .GPS-based monitoring data indicated new cone of depression has been formed. After detail investigation and analysis, it was thought that the appearance of the new subsidence center is the direct consequence of the construction of high-rise building. In this study, based on acquired monitoring data of subsidence, a special software package of Adina computer programs was applied in this study and analysis of the mechanism of subsidence induced by buildings. The results indicate that this method is useful to manage the land subsidence problem to high-rise building group.

Microstructures of different soil layers caused by the high-rise building group in Shanghai

The engineering characteristics of soils are controlled by the state of the microstructure of soils to a great extent. With the withdrawal of groundwater controlled reasonably, the engineering-environmental effect of the high-rise building group becomes the main cause of land subsidence in Shanghai. This paper studied the microstructure of each soil layer under the building loads in the centrifuge model by the scanning electron microscopy and the mercury intrusion porosimetry (MIP) for qualitative analysis and quantitative analysis, respectively. The shape, size and contact condition of the basic unit of the soil microstructure were analyzed. The pore structure of each soil layer was studied by MIP, and the pore distribution of each soil layer was studied by the fractal theory. The ink-bottle effect exists in the intrusion stage in the MIP test. There are four different fractal dimensions for silty clay of layer No. 4 and clayey soil of layer No. 8 and three different fractal dimensions for silty sand of layer No. 7 and layer No. 9. The micro and macro mechanisms of land subsidence caused by the high-rise building group were analyzed.

Land subsidence and pore structure of soils caused by the high-rise building group through centrifuge model test

In the urban area of Shanghai, the dewatering of groundwater was controlled strictly and the engineering–environment effect of the high-rise building group became to be the main cause of land subsidence in Shanghai. Based on the high-rise building group in the soft soil area in Shanghai, the mechanism of land subsidence was studied in this paper by the centrifuge model test. The central area of the building group has larger subsidence and the subsidence superimposition effect is obvious. It can exceed the allowance and cause land subsidence hazard. The land subsidence affected by the different building distances was also studied. For smaller building distances, the subsidence superimposition effect is more obvious. The engineering characteristics of soils are controlled by the state of pore structure of soils to a great extent. The parameter of specific subsidence was put forward as a tie to analyze the relationship between land subsidence and pore structure of soils. The pore structure of each soil layer was studied by the mercury intrusion porosimetry test (MIP) and the pore distribution of each soil layer was studied by the fractal theory. There are mainly macropores in silty clay of layer no. 4, clayey soil of layer no. 8, silty sand of layer no. 7 and layer no. 9 in Shanghai. The ink-bottle effect exists in the intrusion stage in the MIP test. There are four different fractal dimensions in silty clay of layer no. 4 and clayey soil of layer no. 8 and three different fractal dimensions in silty sand of layer no. 7 and layer no. 9.

Centrifuge modeling of land subsidence caused by the high-rise building group in the soft soil area

With the increase of the high-rise buildings, land subsidence induced by human activities becomes a major problem. Land subsidence occurs slowly, but the accumulation results in the cracks in the road, the damage to the pipelines and in the tilting or the cracking of the buildings. With the withdrawal of groundwater controlled reasonably, the engineering-environmental effect of the dense high-rise building group comes to be the main cause of land subsidence. Based on the high-rise building group in the soft soil area in Shanghai, the mechanism of land subsidence is studied in this paper by the centrifuge model tests. The central area of the building group has larger subsidence and the subsidence superimposition effect is obvious. It can exceed the allowance and cause land subsidence hazard. The land subsidence affected by the different building distances is also studied. For smaller building distances, the subsidence superimposition effect is more obvious. The larger excess pore water pressure in the pile-base supporting layer of the central area shows that the stress superimposition effect is larger. The earth pressure under the buildings fluctuates by the disturbance of the pile tips.

Model test study of land subsidence caused by high-rise building group in Shanghai

The paper discusses the influence of a group of high-rise buildings on land subsidence, based on a modeling exercise. The model consisted of five layers of soils typical of the Shanghai area, with the buildings placed on piles set in the upper silty sand horizon. It was loaded to represent the construction sequence of the four buildings. The main settlement was observed to be in the underlying clayey layer. The model demonstrated the increase in pore water pressure with staged loading, its effect on deformation and the increase in effective stress over time. It indicated the largest amount of settlement over time occurs between the buildings.