Asaoka Method Research Articles

Prediction of dredged soil settlement based on improved BP neural network

Based on the measured settlement data from the Reclamation Project of Eastern Hengsha Shoal, two improved BP neural networks optimized by the particle swarm optimization (PSO) algorithm and genetic algorithm (GA) respectively are employed to predict the long-term consolidation settlement of the dredged soil in the reclamation area. By comparing the prediction results of the improved neural networks with those obtained from standard BP neural network and various curve fitting methods including hyperbola method, Hoshino method, and Asaoka method, as well as field-measured data, the improved neural network methods are validated to have a better predictive performance. The error analysis results indicate that compared with the standard BP neural network and curve-fitting prediction methods, the improved BP neural networks exhibit smaller prediction errors in terms of MAE, MSE, RMSE, MAPE, etc., and have a closer match between the predicted settlement values and the actual values. The selected GA-BP and PSO-BP neural network prediction methods in this study demonstrate higher prediction accuracy. Meanwhile, GA-BP demonstrates higher prediction accuracy and generalization ability than PSO-BP, but PSO-BP shows faster convergence in terms of prediction speed. The preferred methods presented in this paper exhibit good robustness and high reliability, which can achieve accurate prediction of dredged soil settlement. Additionally, unlike the traditional curve-fitting methods, the selected methods can effectively reduce the influence of subjective factors during the settlement prediction, and provide a new approach for settlement prediction, which can be effectively utilized as a substitute for long-term settlement monitoring and give reference for the design of settlement control of foundation of further construction projects.

Penerapan Soil Preloading, PVD, dan PHD untuk Analisis Penurunan Konsolidasi Tanah

Soft clay has a low bearing capacity, high compressibility and low permeability. This condition causes soft clay soil to have a long settlement time. To overcome this soft soil condition, soil improvement methods are needed. One of the efforts is to use a combination of soil preloading methods, Prefabricated Vertical Drain (PVD), and Prefabricated Horizontal Drain (PHD) methods. Calculating soil settlement with soil improvement is carried out using the Asaoka method, which is a field observation method, and the theoretical method using the Terzaghi method. Based on the calculation results of field observations using the Asaoka method, the average degree of soil settlement is 93.5%. The calculation results of the Asaoka method are recalculated using a back calculation to produce a new parameter value, namely the horizontal consolidation (Ch) value, which is then compared with the Ch value in the previous plan. In the Terzaghi method, the average soil settlement value is 1.205 meters. The results of soil settlement value are used to analyze the height of the embankment based on the load ratio requirement in SNI 8460: 2017, where the load ratio on the ground is ≥ 1.3 times the planned load under service conditions. Based on the monitoring results, a load ratio value of 0.875 was obtained so that the SNI requirements carried out a re-planning of the landfill. Then, proceed with the design of PVD and PHD. The results obtained in planning use triangular PVD patterns with a distance between PVDs of 1 meter.

Prediction Analysis on Coefficient of Consolidation Values in Improved Soft Clays

Consolidation is a phenomenon in soil mechanics that often causes geotechnical problems. One solution to overcome consolidation phenomena is by speeding up process of pore water pressure dissipation. The type of soil improvement to upgrade the performance of soft clay is by applying pre-fabricated vertical drain (PVD) and pre-compression simultaneously. Geotechnical instrumentations such as settlement plates, piezometers, and inclinometers were installed at the field of study to monitor magnitude of settlement during consolidation process. After the final settlement was achieved, the consolidation parameters such as coefficient of consolidation, and rate of settlement, were back calculated. Prediction analysis of consolidations parameters was performed by means of Asaoka method. The results of this study is very interesting and provide useful engineering information. It is interesting to note that this case study may be beneficial use to practicing engineers and researchers.

Percepatan Proses Konsolidasi Tanah Lempung Dengan Aplikasi Tekanan Vakum dan Drainase Vertikal

This paper presents the performance of PVD and vacuum consolidation as ground improvement method at the construction of Kayu Agung – Palembang Toll Road. The analysis was based on observation data collected between STA 00+000 and STA 09+000. The PVD was installed to a depth where the conus resistance of 80 kPa was achieved. Thus, the length of PVD varies from 5 to 13 m while the actual depth of clay deposit could reach 20 m. As many as 42 settlement plate data were collected and analyzed using Asaoka method to obtain the predicted final settlement, the coefficient of consolidation and the time to reach 90% degree of consolidation. The results were compared with the duration of vacuum consolidation application and the recorded settlement when the vacuum pressure was stopped i.e., when settlement plate recorded no differential settlement in three readings. The duration of vacuum consolidation application generally longer than the t90 predicted by the method and the actual settlement was larger than the predicted final settlement. This study concluded that the variation of the t90 and the magnitude of settlement at t90 have close relationship with the length of PVD and the condition of the soil layer.

PERBANDINGAN PENURUNAN KONSOLIDASI METODE TERZAGHI DENGAN ASAOKA PADA VACUUM PRELOADING

Around 20 million hectares of Indonesia's total land area, or more than 10%, has soft soil. Soft soils can be problematic in construction projects due to their low bearing capacity, high water content, limited permeability, and high compressibility. Vacuum preloading, a technique to hasten consolidation by employing atmospheric pressure from the vacuum as a surcharge load, is one of the improvements for soft soil. The Terzaghi method is typically used to calculate the prediction of the final settlement and the time to reach the final settlement, however the forecast of settlement by the Terzaghi method produces better results than the actual settlement. To estimate the final settlement that takes place in the field, a method with a reliable level of accuracy is used—the Asaoka method. The main goals of this analysis are to determine the final settlement using the Asaoka method, the time needed to reach the final settlement using the Asaoka method, the degree of consolidation caused by vacuum preloading, and soil parameters that support notable differences between the Terzaghi method and Asaoka method using back analysis. According to both site reviews, the Terzaghi method produced settlement outcomes that were 36% and 79% higher than those obtained using the Asaoka method. The time required to reach 90% consolidation on both site reviews are 252 days and 196 days. The results of the Asaoka method used to calculate the degree of consolidation on both site reviews are 92.33% and 94.47%. The value of compression index (Cc), which was derived by back analysis calculations, is what most strongly supports the significant outcomes between the Terzaghi method and the Asaoka method.

Consolidation settlement prediction and monitoring of toll road embankment at STA 23+650 Semarang–Demak Toll Road section

The development of toll road projects in Indonesia is experiencing rapid growth. However, due to the large number of toll roads being constructed over soft soil areas, it is crucial to address the issue of consolidation settlement. This is because settlement can lead to differential or excessive settlement, which potentially damages the structures built on such soil. Unfortunately, consolidation settlement on soft soils is a time-consuming process. Thus, a consolidation acceleration method is needed, one of which is to use a combination of PVD–Preloading. This method can also increase the soil’s bearing capacity, thereby contributing to the preservation and protection of systems that support human activities while maintaining a balance with nature. Therefore, this study aims to investigate consolidation settlement employing PVD–Preloading methods. The analysis focused on a case study conducted at STA 23+650 of the Semarang-Demak Toll Road section. The analysis employed the Asaoka method, integrating field monitoring instruments, along with the Terzaghi method for one-dimensional consolidation. The results showed that the settlement results from the Asaoka and Terzaghi methods correlate with the settlement plate instrumentation in the field.

Experimental analysis on the consolidation of Tunis soft soil improved by multiple Prefabricated Vertical Drains

The purpose of this paper is to experimentally investigate the consolidation of the reconstituted Tunis soft soil ‘TSS’ improved by Prefabricated Vertical Drains PVD. After geotechnical characterization, a consolidation test with vertical loading is performed on a mutli-drains cell, i.e. cell with soil improved by three drains installed in triangular pattern. The PVD used in this study is the Mebradrain 88 (Mb88) type which is commonly used in previous soil improvement projects in Tunisia. The test is conducted through a specific laboratory test apparatus “consolidometer”. The settlements of soft soil specimen were measured during the consolidation test. Soil samples were extracted from different positions to measure water content ω variation after consolidation test. Results show that a significant water content reduction is observed after consolidation tests (approximately 64%) mainly at the vicinity of the PVD. Finally, the assessment of consolidation settlement was investigated using Asaoka’s method. It’s found that the ultimate settlement predicted by Asaoka method showed a good agreement with the measured value with difference less than 1%.

Prediction of Post-Construction Settlement of Road Embankment on Soft Soil Deposits

Organic soils are often considered problematic soils around the world due to several reasons. Excessive settlement is one of the main concerns when constructing infrastructure on soft grounds with organic soil deposits. Ground improvement is mainly carried out on the sub surfaces that lack the strength and stability to bear the structure to be constructed and undergo large settlement during operation. Different soft-ground treatment methods must be applied based on the soil properties to reduce the expected settlements during construction and operation periods. In this context, it is essential to know the behaviour of the subsurface after the ground improvement process. This study mainly investigates the accuracy of the settlement prediction methods during the post-construction stage of the Colombo-Katunayake Expressway Project in Sri Lanka. Settlement prediction was done for the Defect Liability Period using the hyperbolic method, the Mesri method and the Ladd method. A comparison of the predicted settlement with the measured field settlement was done to assess the accuracy of the settlement prediction methods. The comparison showed that the hyperbolic method was more accurate and convenient for predicting the settlement of the embankment. KEYWORDS: Soft ground treatment methods; Preloading; consolidation settlement; Asaoka method; hyperbolic method

Long-Term Settlement Prediction of Ground Reinforcement Foundation Using a Deep Cement Mixing Method in Reclaimed Land

The greenhouse foundation method requires a lower allowable bearing capacity compared to general buildings, but the high-spec and expensive prestressed high-strength concrete (PHC) pile reinforcement method is mainly applied. Therefore, the deep cement mixing (DCM) method, which is one of the ground reinforcement foundations that replaces the PHC piles and secures structural safety suitable for the greenhouse foundation, was considered. To verify the structural safety of the DCM method, a geotechnical survey and soil test were conducted, and a long-term settlement monitoring system was established. The specifications of the DCM foundation were designed to be 0.8 m in diameter, 3 m × 3 m in width and length, and 3 m in depth. Based on the settlement monitoring data, long-term settlement was predicted considering the greenhouse durability of 15 years. For long-term settlement prediction, the Log S–T, hyperbolic, Asaoka method, Schmertmann theory, and the finite element method (FEM) analysis were performed. In the case of the Log S–T, hyperbolic, and Asaoka method based on actual measurement data, the settlement amount was predicted to be 12.18~20.43 mm, and in the case of the Schmertmann empirical formula, it was predicted to be 19.66 m. The FEM analysis result was 8.89 mm. As the most conservative result, the DCM foundation method designed in this paper had an allowable bearing capacity of 310 kN/m2 and a long-term settlement of 20.43 mm. This is the result of satisfying both the allowable bearing capacity of 100 kN/m2 and the allowable settlement range of 25.4 mm as a foundation. Through this study, it was proven that long-term structural safety can be sufficiently secured when the DCM foundation is constructed on a soft ground through a design that considers the required service life and allowable bearing capacity of the structure. In addition, it was confirmed that the Hyperbolic, Asaoka, and FEM analysis method adopted in this paper can be applied to the long-term settlement behavior analysis of the DCM foundation method.

Settlement Prediction of Reclaimed Coastal Airports with InSAR Observation: A Case Study of the Xiamen Xiang’an International Airport, China

Many coastal cities reclaim land from the sea to meet the rapidly growing demand for land caused by population growth and economic development. Settlement in reclaimed land may delay construction and even damage infrastructures, so accurately predicting the settlement over reclaimed areas is important. However, the limited settlement observation and ambiguous final settlement estimation affect accurate settlement prediction in traditional methods. This study proposes a new strategy to solve these problems by using the Multitemporal Interferometric Synthetic Aperture Radar (MT-InSAR) method and takes the Xiamen Xiang’an International Airport, built on reclaimed land, as an example. The MT-InSAR is adopted to process the Sentinel-1 images to obtain the settlement history of the study area. The results show that settlement mainly occurs in the reclaimed areas, with the maximum average settlement rate exceeding 40 mm/y. We use the statistical properties of curve fitting to choose the best curve model from several candidate curve models to predict the settlement time series. The Asaoka method is used to identify the critical state between settlement and stability. We predict the consolidation time of the whole study area and reveal that the deformation rate is positively correlated with the consolidation time. The maximum remaining settlement time is over ten years since 24 December 2019. Therefore, manual compaction operations can be carried out to speed up settlement in the areas that need a long time to consolidate. The proposed method can be used to predict the settlement of similar reclaimed areas, and the predicted results can provide a reference for engineering construction.

PREDICTION OF ROAD CLEARANCE

One method of handling soil that can be done to speed up the consolidation process is to add a Pre-Loading embankment on top of the plan embankment. In addition, this handling is also carried out to achieve a reduction by the design load, so that the settlement of embankment after the construction period still meets the required criteria and standards. This study was conducted to obtain a comparison of the prediction of embankment settlement with the empirical method using CPT data and the prediction of settlement using the Asaoka Method. In addition, the results of the consolidation coefficient will also be compared which can be used to determine the right time for Pre-Loading excavation during the construction period. The data used are CPT test data in the field as well as laboratory test data and measurement data for the settlement plate settlement closest to the position of the CPT test. From the analysis carried out, it is obtained that the prediction of decline using the Asaoka method is smaller than the prediction of decline using the empirical method using CPT data. In addition, from the analysis, it was found that at locations HB-04 and SP 70, as well as HB-07 and SP 91, showed laboratory consolidation coefficient values (cv-Lab.) which were close to the consolidation coefficients of the Asaoka Method (cv-Asa.), while in HB -05 and SP 79 and HB-06 and SP 85 show a large difference in values. The average comparison of the cv-Lab. consolidation coefficients and CV-Asa. is 58.5%.

Deformation analysis of soft ground treated with PVDs – A Numerical study

Soft ground deforms in both vertical and lateral directions when subjected to loads. These soils need to consolidate and gain strength to further use it for different engineering applications. Prefabricated vertical drains are very efficient for deep soil deposits employed with preloading for ground improvement. In this paper, a case study of a container yard in Chittagong port, Bangladesh is used to investigate the characteristics of the soil and its response when they are incorporated with PVDs. Final settlements of 258 mm are predicted using the Asaoka method for 1 m c/c PVD spacing. Numerical analysis is carried out by FEM software Plaxis to evaluate the performance of the PVDs during the consolidation. Different spacing of PVDs is also considered for the study. Settlements of 258 mm and 205 mm are obtained for 1 m and 1.5 m c/c PVDs spacing at the end of 52 days. The present study investigates the variations of both vertical deformations and lateral deformations of soft ground treated with PVDs. Lateral displacements at the end of surcharge loading and surface settlements are calculated.

Settlement Predictions of a Trial Embankment on Ballina Clay

An instrumented trial embankment was constructed on the soft ground with the use of prefabricated vertical drains at Ballina in northern New South Wales (NSW, Australia) as part of the Australian Research Council Centre of Excellence for Geotechnical Science and Engineering (CGSE) research program. Comprehensive geotechnical site investigations were performed and field monitoring data were collected, which make it possible to study and compare various settlement prediction methods. In this paper, the Asaoka method, the Hyperbolic method, and the Bayesian updating approach are employed to predict the settlement of the trial embankment. The predictions of the three methods are compared for different amounts of monitoring data. The results show that the predicted settlements are close to the measurements and the accuracy of the ultimate settlement prediction can be improved by incorporating more monitoring data. The time increment can significantly influence the accuracy of the result predicted by the Asaoka method. The Bayesian updating approach is in agreement with the observed settlement by using only 215 days of the monitoring data. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman,serif;}

Compressibility and stability analysis of an embankment on soft soil: a case study

This paper reports on the performance analysis of an embankment over a soft soil deposit during construction. The study section is part of the duplication of the Brazilian federal highway, BR 470, a major infrastructure project that crosses several soft clay deposits in the state of Santa Catarina, Brazil. To guarantee stability and accelerate the landfill consolidation, the project provided geotechnical solutions as follows: basal reinforcement with geogrids, equilibrium berms, stage constructions of the landfill (slow construction), preloading and prefabricated vertical drains. The performance during field construction was mostly evaluated through instrumentation considering the evolution of horizontal displacements (distortion and distortion rates) and the Asaoka method to evaluate the stabilisation of settlements. Given the limitations of the methods used for control during construction, and a discrepancy between field settlements and original project predictions, the soil profile and geotechnical parameters were revaluated during construction and used in a revised performance analysis. Some important considerations were observed from this back-analysis that could have been used to modify the construction process during execution. In addition, to analyse the effects of the inherited variability, a sensitivity analysis to determine levels of possible settlements and time of consolidation was performed.

Determination of the ultimate consolidation settlement of jack-up spudcan footings embedded in clays

When jack-up platforms are deployed for long-term services such as those functioning as production units, the consolidation settlement of spudcan footings is an issue of particular concern. Unpredicted and thus unprepared settlement may do harm to the serviceability and safety of jack-up rigs. Through centrifuge experiment and large deformation finite element calculation, this paper first illustrates the inherent correlation between the excess pore pressure dissipation inside soil and spudcan settlement development. With the measured and calculated settlement time histories, subsequent efforts are directed towards exploring how to predict the ultimate consolidation settlement with accuracy. Particular attentions are placed on investigating the applicability and advantages of two observational methods: Asaoka's method and Hyperbolic approach. Their prediction performances for spudcan with various soil, loading, embedment and geometrical conditions are symmetrically evaluated through numerical parametric investigation. The upper and lower limits of their prediction errors are established. Explicit recommendations are given on the selection of appropriate prediction approaches for different consolidation conditions. The practical significance of these research outcomes lies in 1) providing guidance on the selection of settlement prediction approaches; 2) establishing the limits of prediction errors involved. These are expected to be particularly useful for the field monitoring of spudcan settlement.

EVALUASI KINERJA VERTICAL DRAIN PADA PROYEK JALAN TOL DI SUMATERA DITINJAU DARI ASPEK KONSOLIDASI

Over time, there has been more development, this has made less land for development. However, development still has to go on. One of the infrastructure that is currently needed is toll roads to increase the efficiency of movement from one place to another. One of the serious problems at this time is that many soils have small bearing capacity and large settlement, for example, such as soft soil. In order for this model soil to have a stable condition, the solution is loaded so that the pore water from the soil can be pressed out. However, it takes a long time to achieve the desired settlement, here the prefabricated vertical drain method is used to accelerate the settlement. Prefabricated vertical drain here makes the distance between the pore water that was previously thick as soft soil, to half the distance between prefabricated vertical drains. The analysis calculation in this thesis uses the one dimensional consolidation method, the finite element method, and the asaoka method as the calculation of the actual results from field data. The results of this study found that the difference in the degree of consolidation between the theoretical calculations and the Asaoka method was 3.4303%.

Application of Wavelet Neural Network in Building Settlement Prediction

Deformation monitoring, as a key link of information construction, runs through the entire process of the building design period, construction period and operation period[1]. At present, more mature static prediction methods include hyperbolic method, power polynomial method and Asaoka method. But these methods have many problems and shortcomings. In this paper, based on the characteristics of building foundation settlement and the methods widely discussed in this field, a wavelet neural network model with self-learning, self-organization and good nonlinear approximation ability is applied to the prediction problem of building settlement[2]. Using comparative analysis and induction method. The 20-phase monitoring data representing the deformation monitoring points of different settlement states of the line tunnel, using the observation data sequence of the first 15 phases respectively to take the cumulative settlement and interval settlement as training samples, through the BP artificial neural network and the improved wavelet neural network, for the last five periods Predict the observed settlement.Through the comparison, it is found that whether the interval settlement or the cumulative settlement is used, the prediction results of the wavelet neural network are basically better than the prediction results of the BP artificial neural network, and the number of trainings is greatly reduced. The adaptive prediction of the wavelet neural network. The ability is particularly obvious, and the prediction accuracy is significantly improved. Therefore, it can be shown that the wavelet neural network is indeed used in the settlement monitoring and forecast of buildings, which can obtain higher prediction accuracy and better prediction effect, and is a prediction method with great development potential.

The Study of The Usage of Vacuum Preloading Method in The Construction Project Of Palembang – Indralaya Toll Road

Palembang – Indralaya (Palindra) Toll Road is part of the Trans Sumatera Toll Road built on soft soil. Soil improvement using vacuum preloading method has been conducted to resolve the problem. The method involves replacing a surcharge load with an atmospheric pressure and utilizing vertical and horizontal drains, as well as sand blanket. Factors that influence the effectivity of the performance of the vacuum method comprise the settlement, the time of settlement, the speed of settlement, the degree of consolidation, the distance of the Prefabricated Vertical Drain or PVD, and so forth. The result of the settlement using Terzaghi’s equation combined with Indraratna’s showed that the addition of the height of the fill would have been effective if it had been equal or larger than the vacuum pressure that was used (80 kPa). It could be observed from attaining faster consolidation time of 56 days. The analysis result was, then compared with the final settlement by using Asaoka method. The design of the PVD distance by using vacuum method showed that the spacing (S) was less restrained, which was 1,23 m, compared to the one using with extra load (surcharge) which was 1,2 m. The settlement of vacuum consolidation was 1,98 m, which was smaller than the surcharge one that reached 2,11 m.

The Performance of the Nailed Slab System-Supported Embankment on Peat Soil

This study presents the effect of pile length and connection with the performance of the nailed slab system as supporting embankment load on peat soil. Various times-settlement performances that have reflected different piles length and connection have been observed. The consolidation settlement behavior at several models has been simulated using Asaoka method in order to obtain the coefficient of consolidation. It has been obtained that the nailed slab system is able to decrease the stress distribution in the soil foundation. This can have a significant effect on the stability embankment, and hence, the type of connections pile with the slab will specify for the embankment load on peat soil. The addition of the pile element under the slab can contribute to the resisting forces, reducing consolidation settlement, increasing slab stiffness, and hence the overall stability of the embankment.

Métodos hiperbólico y Asaoka, otros usos. Caso del equilibrio de la humedad de suelos no saturados. Aplicación.

Este artículo presenta la validación práctica del método hiperbólico y el de Asaoka para predecir la humedad final a la que llegaría una muestra de suelo tras someterla a una cierta succión matricial; basta con disponer de varias determinaciones de humedad durante el ensayo. Se logra así acortar muy notablemente los tiempos de los ensayos de succión sin apenas pérdida de precisión en su determinación. Para ello, se han analizado 3 referencias bibliográficas de ensayos de succión matricial en suelos y una serie de ensayos propios, específica para los propósitos del presente artículo. El artículo describe los 4 suelos y las técnicas de succión empleadas y presenta, para las diferentes succiones, los registros de la evolución de la humedad empleados. El análisis de éstos evidencia que ambos métodos, y en mayor medida el hiperbólico, permiten predecir la humedad final de las muestras a partir de registros tempranos. Adicionalmente, el buen ajuste con el método de Asaoka sugiere que la difusividad hidráulica, D(θ), parámetro que rige la velocidad de este proceso de difusión de humedad, es poco variable durante el ensayo. Por ello, se propone este método para estimar D, difícil de determinar experimentalmente. El desarrollo teórico de los dos métodos se recoge en un artículo previo.