In order to characterize the attenuation of ground vibration with distance and characteristics of ground vibration at sites in Tainan Area of STSP, a series of small-scaled in-situ vibration tests and traffic-induced ground vibration measurements were conducted. The tests includesing four drop hammer tests and five shaking tests which were performed on the ground surface, on shallow foundation (footing), on single pile foundation, and on proto-type pile foundation, respectively. As for the traffic-loading induced ground vibration measurements, a total of ten high speed trains running with various speeds and four cases for heavy trucks running were measured.
From this study, it concludes that the dominant frequency, amplitude, and attenuation coefficients of ground vibration at the test site are influenced by different source types, energy level, foundation type, interface area between soil and foundation, as well as the foundation size and stiffness. Conclusions also show that the levels of ground vibration induced by heavy truck are significant at small distances. Therefore, for the design of high-tech fabs in STSP, both the ground vibrations induced by the THSR and the heavy trucks have to be considered to meet their operational requirements.
The dynamic compaction method, with the advantages of fast and low cost, is a technique often used for ground improvement of reclaimed land. Precautions of this technique focus on damage control for the proximity structures if the vibration induced by the impact of heave falling weight to the ground exceeds certain levels. Peak Particle Velocity (PPV) is generally treated as the index for vibration control in many academic literature and technical specifications as it is the observable response of the energy carried by the vibration waves. Results of several trial sets of dynamic compaction and rapid impact compaction tests are analyzed to evaluate the effectiveness of vibration reduction with different trench layouts, and the influences of compaction layout, compaction energy, and ground composition to the PPV. A correlation between the normalized PPV and distance derived based on regression analyses is proposed as a reference for future similar engineering projects.
Site Response Analysis Approach via Generic Profile Correction
傳統大地工程地盤反應分析係將岩盤設計地震輸入於符合相同地盤條件(如Vs30 = 760 m/s)之基盤露頭，以一維動力分析求得地震波經由土層剖面傳遞至地表或結構基礎面之振動，作為考量現地場址放大效應之設計地震，可供後續結構動力分析的輸入運動使用。
上述岩盤設計地震透過地震危害度分析獲得，是為在特定年超越機率下之場址均佈危害度反應譜(uniform hazard response spectrum, UHRS)，其過程中對於地震動之評估係基於由地表測站實測地震動資料所建立的地震動評估模型(ground motion prediction equation, GMPE)。近期發展之地震動評估模型，除考慮震源特性對地震動之影響外，亦包括採用以地表下30公尺平均剪力波速(Vs30)為指標的場址項，即可包括測站淺層土壤特性受到地震動影響之地盤放大效應評估。故，UHRS在經由地震動評估模型時已存在一般震源下特定Vs30的地盤放大效應。因此，若仍直接將其置於特定Vs30基盤露頭並考慮場址之土層剖面，進行一維波傳分析，將重複考慮在基盤以下土層之地盤放大效應。
美國DCPP(Diablo Canyon Power Plant)核電廠在獲得Vs30為760m/s的均佈危害度反應譜後，擬以地盤反應分析程序求得地表處之地震動時，鑒於地震動評估模型所評估得之均佈危害度反應譜已存在地盤放大效應之事實，且Vs30僅能代表淺層土壤特性，並無法完全實際反映深層土壤經不同地震動所引致之地盤放大。因此，提出以相同輸入地震進行兩次地盤反應分析求得真正場址地盤放大倍率之程序。以符合場址控制地震之點震源經通用地盤剖面(generic rock profile)求得與建立均佈危害度相符之輸入地震，同樣置於深部岩盤半無限域處分別經由通用地盤剖面(generic rock profile)與場址整體地盤剖面傳遞至地表面，此二組土層剖面於地表輸出之比值，即為該場址之地盤放大函數，再經此放大函數乘上均佈危害度反應譜後，即可得出整體場址土層剖面在此地震情境下考量現地場址地盤放大效應(amplification effect)之地表振動。本文進一步以案例分析，探討傳統地盤反應分析與DCPP電廠之地盤反應方法對分析結果之差異，並說明其影響。
For the traditional site response analysis method, the design earthquake, also known as UHRS (Uniform Hazard Response Spectrum), is assigned at the rock outcrop, such as Vs30 = 760m/s. In this analysis, a one-dimensional wave propagation program, like SHAKE, was used to calculate the response at ground surface and foundation level for further structural dynamic analysis and seismic design.
The UHRS from seismic hazard analysis is based on Ground Motion Prediction Equation (referred to as GMPE). Since the GMPE is based on the strong motion measured at the ground surface, it has implications of the site effects when earthquake waves propagated through the layers. Therefore, when we use the traditional method to calculate the site response, some of the amplification effects would be repeatedly considered, leading to conservative results.
This paper refers to the practice of the DCPP (Diablo Canyon Power Plant) in the United States. First, the point source model is used to generate the input motion at the hard bedrock (Vs ≥ 2800 m/s) of the generic profile. Next, the linear site response analysis of the whole generic profile is conducted by using this input motion and if the resulting surface spectrum at the generic profile is similar to UHRS then the input motion at hard bedrock is consistent with seismic hazard. Then the nonlinear site response analysis of the site-specific profile merged with generic profile is calculated with the same input motion to obtain the site ground motion. By taking the ratio of these two sites responses, the site-specific amplification function would be determined. Hence the site Ground Motion Response Spectrum (GMRS) and the Foundation Input Response Spectrum (FIRS) could be got by multiplied UHRS with amplification function.
The comparison of the ground motions between traditional and modified procedures of site response analysis will be discussed and revealed in this paper.
Based on the geological investigation results of five harbors in Matsu, this paper reports the preliminary study results on the liquefaction potential of five harbors and the seismic performance of the Fuao harbor. The geological condition and the soil strength of each harbor is described first. Subsequently, the dynamic properties of some soil samples taken from selected sites, studied by the resonant column, are discussed. The ground liquefaction potential of each sites was then evaluated by a dynamic analysis using Plaxis. The results of the analysis case are consisyent with the soil liquefaction potential analysis results.
Measurement of environmental micro-vibration is important, especially for the sites near a Hi-tech Park where high-speed trains across. The purpose of this paper is to discuss a technique and an analysis method of micro-vibrational measurement. The basics of wave, vibration criteria, vibrational measurement equipment, and analysis method are included. The paper focuses on the study the environmental vibration of southern hi-tech park. The measurement results show that the variation of the vibration values are about 7 to 10dB between day and night times. The effect of high speed rail (HSR) on vibration decreases with increasing travel distances of the HSR. The major frequency effect of HSR of amplitude ranged from 3.15 to 12.5Hz. However, the major frequencies created by the HSR are 6.3Hz and 10Hz. The 3.15Hz is the fundamental frequency of soil deposit. Isoseismic map can be helpful to understand the ground vibration influence of the hi-tech park when the HSR trains pass through.
For the construction route of this project, the shield tunnel has to overcome the challenges given by the complex formation of the cobble and gravel, rock and conglomerate interface at the same time. Since it is located in a scientific park, the owner has high requirements on the ground surface vibration. Therefore, the shield tunnel machine type, cutter head, and screw conveyor and construction management have become the key success of this project. This paper mainly discusses the design, construction considerations of the shield tunnel, as well as the arrival of the shield in the water, the selection of the shield machinery, the construction management countermeasures and the on-site vibration measurement results. It is hoped that the results of this paper would serve as a reference for future projects of similar characteristics.
The Kaohsiung Light Rail Transit (LRT) system is considered as the first embedded rail system in Taiwan. However, domestic engineering consultants are still lacking experience for analysis, design, and construction of embedded rail systems. Ground-borne vibrations of the mass rapid transit system is an important environmental issue in urban environments. In order to understand the environmental impact of ground-borne vibrations caused by a train running on the rail system, this paper establishes both experimental measurements and numerical analysis models to perform experiment and simulation studies. The Kaohsiung LRT is used as a case study. Firstly, the field experimental method is carried out for the on-site vibration test of Kaohsiung light rail transit, and the vibration velocity and displacement of the train passing through are measured. Secondly, the real embedded rail track system is modeled using ANSYS software with finite element analysis and the dynamic time history of the vibration response of the rail caused by a moving load is obtained. Both the experimental and analytical results for ground-borne vibration at specific points are compared and discussed. The proposed procedure is promising to be suitable for practical vibration analysis and reduction for rail systems.
The September 6 2018 Hokkaido Earthquake was a MJ=6.7 earthquake occurred in the eastern part of Iburi in southern Hokkaido, Japan. This moderate magnitude earthquake caused surface vibrations in Iburi with a Japanese intensity scale of 7. Due to the unique volcanic ash deposit, the earthquake caused strong ground motion and soil liquefaction resulting in the damage of the building with shallow foundation, pipeline, and the retaining wall in the urban area of Sapporo, and triggered a lot of landslides in Atsuma, which buried house and caused tens of deaths. In Sapporo, the damage due to the loss of saturated sand in the Satozuka area was the most serious one, causing serious settlement and tilt of the building with shallow foundation. The generator sets of Tomato-Atsuma Thermal Power Station were damaged and shut down during the strong earthquake, causing the blackout in whole Hokkaido area. The reconnaissance team of NCREE investigated the disaster area in September 2017 and collected relevant data. This summary report included the seeing and learning experience based on the reconnaissance, and is intended to sharing with the geotechnical communities.