DE202022101355U1 - A system for pile design considering downward resistance - Google Patents

Abstract

A system for designing piles considering downward resistance, the system comprising:
a data acquisition unit configured to receive load data from piles and soil data;
an analysis unit connected to the data acquisition unit to create either a soil or a pole model; and
an optimization unit connected to the analysis unit to perform a static incremental analysis of the pile and the soil model, thereby evaluating the bearing capacity and the deformation of the pile using a limit curve.

Description

FIELD OF THE INVENTION

The present disclosure relates to piling design techniques. More particularly, the present disclosure relates to a system for pile planning considering downside resistance.

BACKGROUND OF THE INVENTION

A pile driven into a compacting layer of soil is subject to negative friction caused by the subsidence of the soil relative to the pile. As a result, additional downward tension develops in the pile and it experiences additional displacement. Designers of piling foundations have long addressed the need to account for the effects of negative friction, but there has been much confusion as to how negative friction affects pile behavior.

Up to now, manual methods have been used to estimate the settlements and the maximum load at the pile head. The hand method assumes that the pile - the ground - is completely slipping, and the results agree well with computer analysis and field monitoring when ground subsidence is very small in the open field or becomes very small in the lower part of the pile.

The practical design approach to estimating the bearing capacity (resistance) that can withstand the maximum external load at the head of a pile neglects negative friction. The bearing capacity must meet the condition that the pile head displacement reaches an acceptable limit, regardless of the settlement of the soil.

In existing prior art, the boundary element method assumes that the soil around a pole can be represented by an elastic continuum, with a limitation on the stresses that can develop at the pole-soil interface. The pile is divided into a series of elements whose vertical movement is related to the applied load, pile-soil interactions, compressibility of the pile and displacement of its tip. By considering the compatibility of the incremental pile and soil motion at each element, one obtains the equations when the pile-soil interface conditions remain in the non-failure state. Solving the equations together with the equilibrium equations gives the incremental pile-soil stresses and pile tip displacements, from which the axial force and vertical displacement distributions within the pile can be calculated.

However, it turns out that when designing piles, taking negative friction into account, it is necessary to estimate the load, the bearing capacity and the balance between them (equilibrium of forces), as well as the pile displacement, the settlement of the subsoil and the balance between them (equilibrium of settlement).The behavior of the pile is not only the load-bearing behavior or the pile displacement at the pile head, it is much more important to evaluate the force and settlement balance along the pile length.

In view of the previous discussion, it is clear that a system for pile construction that takes downward resistance into account is required.

SUMMARY OF THE INVENTION

The present disclosure aims to provide a simplified system for the design of piles taking into account the downward resistance for pile foundations.

In one embodiment, a system for pile design considering downside resistance is disclosed. The system includes a data acquisition unit configured to receive load data from piles and soil data. The system further includes an analysis unit connected to the data acquisition unit to generate either a pole or a soil model. The system also includes an optimization unit connected to the analysis unit to perform a static incremental analysis of the pile model, evaluating the load-bearing capacity and the deformation of the pile using a limit curve.

In another embodiment, the load data are external loads acting on the piles and the soil and come from the superstructure calculation, the pile data being the pile diameter and the pile length, and the pile data and the soil data being used to calculate the pile bearing capacity .

In another embodiment, the pole model is an elastic relationship and a ground-to-pole model is elastoplastic.

In another embodiment, the piles are designed taking negative friction into account such that the force balance plane (FEP) coincides with the settlement equality plane (SEP).

In another embodiment, the piles are installed in a consolidating soil such that the load distribution along a pile under the force equality condition must be less than or equal to its bearing capacity.

In another embodiment, the area load acting on the pile increases due to the potential mobilization of negative head-to-toe friction, and the distributed pile bearing capacity decreases due to the corresponding mobilization of positive head-to-toe friction. The mobilization of friction ranges from zero to the calculated maximum values.

In another embodiment, subsoil settlement is caused by loads acting on the soil beneath the slab. The minimal settlement is due to the part of the load from the superstructure carried by the slab, the further settlements can be considered as follows: due to the effects of the pile-soil interaction; due to the lowering of the groundwater level and; due to other external loads.

In another embodiment, when the pile displacement is equal to the possible ground settlement, the friction at the pile-soil interface changes from positive to negative (or vice versa), while when the pile displacement is greater than the ground settlement, positive friction occurs , where if the pile displacement is smaller than the soil settlement, negative friction occurs.

In another embodiment, if the FEP is below the SEP, piles are assumed to be able to bear external loads since its bearing capacity is greater than the external load, while piles are not able to bear the load , when the FEP is above the SEP, which means its carrying capacity is smaller than the external load.

In another embodiment, individual values such as the positive or negative friction at the pile-soil interface, the bearing capacity of the pile base and the settlement of the soil are only estimated and are not real values. If these values are checked and validated together at SEP and FEP, errors can be avoided.

The aim of the present disclosure is to develop a system for dimensioning piles taking into account the downward resistance.

Another goal of the present disclosure is to overcome the difficulties of the previous approaches.

In order to further clarify the advantages and features of the present disclosure, a more detailed description of the invention is provided by reference to specific embodiments that are illustrated in the accompanying figures. It is understood that these figures represent only typical embodiments of the invention and are therefore not to be considered as limiting the scope thereof. The invention is described and explained in more detail with reference to the accompanying figures.

character list

• 1 ein Blockdiagramm eines Systems für die Pfahlkonstruktion unter Berücksichtigung des Abwärtswiderstands gemäß einer Ausführungsform der vorliegenden Offenbarung zeigt;
• 2 die möglichen Standorte von SEP und FEP sowie die Grenzen der (positiven und negativen) Reibungsmobilisierung und mögliche Bodensenkungen in Übereinstimmung mit einer Ausführungsform der vorliegenden Offenbarung veranschaulicht;
• 3 den Grundriss des Bitexco-Turmfloßes gemäß einer Ausführungsform der vorliegenden Offenbarung zeigt;
• 4 die geschätzten Ergebnisse der Pfahllastverteilung, der Pfahlverschiebung und der Bodensenkung gemäß einer Ausführungsform der vorliegenden Offenlegung zeigt;
• 5 den Vergleich der von PRAB berechneten Neutralebene (SEP und FEP) mit der FEP-Position, die mit verschiedenen Methoden gemäß einer Ausführungsform der vorliegenden Offenbarung bestimmt wurde zeigt; und
• 6 Tabelle 1 mit statistischen Bodenparametern in Übereinstimmung mit einer Ausführungsform der vorliegenden Offenbarung zeigt.

These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying figures, in which like characters represent like parts throughout the figures, wherein:

• 1 Fig. 12 shows a block diagram of a system for pile construction considering downward resistance according to an embodiment of the present disclosure;
• 2 illustrates the possible locations of SEP and FEP as well as the limits of frictional mobilization (positive and negative) and possible subsidence in accordance with an embodiment of the present disclosure;
• 3 Figure 12 shows the plan view of the Bitexco tower raft according to an embodiment of the present disclosure;
• 4 Figure 12 shows the estimated results of pile load distribution, pile displacement and ground settlement according to an embodiment of the present disclosure;
• 5 Figure 12 shows the comparison of the neutral plane (SEP and FEP) calculated by PRAB with the FEP position determined by different methods according to an embodiment of the present disclosure; and
• 6 Table 1 shows statistical soil parameters in accordance with an embodiment of the present disclosure.

Those skilled in the art will understand that the elements in the figures are presented for simplicity and are not necessarily drawn to scale. For example, the flow charts illustrate the method of major steps to enhance understanding of aspects of the present disclosure sern.In addition, one or more components of the device may be represented in the figures by conventional symbols, and the figures only show the specific details relevant to an understanding of the embodiments of the present disclosure to avoid the figures with details that are readily apparent to those skilled in the art familiar with the present description.

DETAILED DESCRIPTION

For a better understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe the same Variations and further modifications of the illustrated system, and such further applications of the principles of the invention illustrated therein, as would normally occur to one skilled in the art to which the invention pertains are contemplated.

Those skilled in the art will understand that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be limiting.

When this specification refers to "an aspect," "another aspect," or the like, it means that a particular feature, structure, or characteristic described in connection with the embodiment is present in at least one embodiment included in the present disclosure. Therefore, the phrases "in one embodiment," "in another embodiment," and similar phrases throughout this specification may or may not all refer to the same embodiment.

The terms "comprises," "including," or other variations thereof are intended to cover non-exclusive inclusion, such that a method or method that includes a list of steps includes not only those steps, but may also include other steps that are not expressly stated or pertaining to any such process or method. Likewise, any device or subsystem or element or structure or component preceded by "comprises...a" does not, without further limitation, exclude the existence of other devices or other subsystem or other element or other structure or other component or additional device or additional subsystems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The system, methods, and examples provided herein are for purposes of illustration only and are not intended to be limiting.

Embodiments of the present disclosure are described in detail below with reference to the attached figures.

In 1 Illustrated is a block diagram of a system for pile design considering soil resistance, according to an embodiment of the present disclosure. The system 100 includes a data acquisition unit 102 configured to receive pile loading data and soil data.

In one embodiment, an analysis unit 104 is connected to the data acquisition unit 102 to create a soil or pole model.

In one embodiment, an optimization unit 106 is coupled to the analysis unit 104 to perform a static incremental analysis of the pile model, evaluating the bearing capacity and deformation of the pile using a bearing capacity limit curve.

In another embodiment, the load data are external loads acting on the piles and the soil and come from the superstructure calculation, the pile data being the pile diameter and the pile length, and the pile data and the soil data being used to calculate the pile bearing capacity .

In another embodiment, the pole model is an elastic relationship and a ground-to-pole model is elastoplastic.

In another embodiment, the piles are designed so that the Equilibrium Force Plane (FEP) coincides with the Equilibrium Settlement Plane (SEP), taking into account negative friction.

In another embodiment, the piles are installed in a consolidating soil so that the load is distributed along a pile must be less than or equal to its carrying capacity under the condition of force equality.

In another embodiment, the area load acting on the pile increases due to the potential mobilization of negative head-to-toe friction, and the distributed pile bearing capacity decreases due to the corresponding mobilization of positive head-to-toe friction. The mobilization of friction ranges from zero to the calculated maximum values.

In another embodiment, subsoil settlement is caused by loads acting on the soil beneath the slab. The minimal settlement is due to the part of the load from the superstructure carried by the slab, the further settlements can be considered as follows: due to the effects of the pile-soil interaction; due to the lowering of the water table and due to other external loads.

In another embodiment, when the pile displacement is equal to the potential subsidence, the friction at the pile-soil interface changes from positive to negative (or vice versa), while when the pile displacement is greater than the subsidence, positive friction occurs , where if the pile displacement is smaller than the subsidence, negative friction occurs.

In another embodiment, if the FEP is below the SEP, piles are assumed to be able to bear external loads since its bearing capacity is greater than the external load, while piles are not able to bear the load , when the FEP is above the SEP, which means its carrying capacity is smaller than the external load.

In another embodiment, individual values such as the positive or negative friction at the pile-soil interface, the bearing capacity of the pile base and the settlement of the soil are only estimated and are not real values. If these values are checked and validated together at SEP and FEP, errors can be avoided.

2 illustrates the possible locations of SEP and FEP as well as the limits of friction mobilization (positive and negative) and possible subsidence in accordance with an embodiment of the present disclosure;

Equality of Forces: Assuming that the piles will be installed in consolidating soil, the equality of forces condition requires that the load distribution along a pile is equal to its bearing capacity. A horizontal plane at the point where the load equals the working load limit is called the "Equal Force Plane - FEP".

$$R_t=A_t{r}_t=A_t{N}_t{\sigma }_{z=D}^{\text{'}}$$

wobei N_t = Koeffizient für die „Tragfähigkeit“ des Pfahlfußes, D = Tiefe bis zum Pfahlfuß, f_z=_D = effektive Überlagerungsspannung am Pfahlfuß, A_t = Fußfläche (normalerweise die Querschnittsfläche des Pfahls).Pile load capacity: Pile load capacity includes base resistance and shaft resistance. One of the researchers believed that foot resistance evolved primarily from compression behavior and had no end value. As the load is increased, the soil volume is compressed to the maximum, but failure or a peak is never reached. Therefore, the toe resistance is only an assumption. It can be assumed that the toe resistance behaves in a similar way to the pressure force in the plate pressure test. Field tests have shown that there are no failure points on the load-displacement curve. The behavior of toe resistance can be simulated by hyperbolic models. Toe resistance can be determined using many methods. For this study, toe resistance is determined by the β method: $${\mathrm{right}}_i=N_t{\sigma }_{\mathrm{e.g}=D}^{\text{'}}$$

$$R_t=A_t{\mathrm{right}}_t=A_t{N}_t{\sigma }_{\mathrm{e.g}=D}^{\text{'}}$$

where N _t = coefficient for the “bearing capacity” of the pile base, D = depth to the pile base, f _z = _D = effective overburden stress at the pile base, A _t = base area (usually the cross-sectional area of the pile).

$$R_s={\displaystyle \underset{0}{\overset{D}{\int }}{A}_s{r}_{s,z}dz=}{\displaystyle \underset{0}{\overset{D}{\int }}{A}_s\left(c\text{'}+\beta {\sigma }_z^{\text{'}}\right)dz}$$

wobei c' = Effektiver Kohäsionsschnittpunkt, ® = Bjerrum-Berland-Koeffizient, /^l, = Effektive Überlagerungsspannung, A_s = Umfangsfläche des Pfahls in der Tiefe z (Fläche über eine Längeneinheit des Pfahls).Shaft drag develops from friction at the soil/pile interface and is characterized by a shear force, so it has a final value. This wave resistance is a real value. The external load is distributed over the length of the pile by the shaft resistance. The remaining load at the base of the pile is carried by the base resistance. The shaft resistance (both negative and positive) can be estimated as follows: $${\mathrm{right}}_{s,\mathrm{e.g}}=c\text{'}+\beta {\sigma }_{\mathrm{e.g}}^{\text{'}}$$

$$R_s={\displaystyle \underset{0}{\overset{D}{\int }}{A}_s{\mathrm{right}}_{s,\mathrm{e.g}}\mathrm{i.e}\mathrm{e.g}=}{\displaystyle \underset{0}{\overset{D}{\int }}{A}_s\left(c\text{'}+\beta {\sigma }_{\mathrm{e.g}}^{\text{'}}\right)\mathrm{i.e}\mathrm{e.g}}$$

where c' = effective cohesion intersection, ® = Bjerrum-Berland coefficient, / ^l , = effective overburden stress, A _s = circumferential area of the pile at depth z (area over a unit length of the pile).

wobei R_t der Fußwiderstand ist, bei dem sich der Boden elastisch verhält, R_s der Gesamtwiderstand der Welle.The distributed carrying capacity can be determined as follows: $$\begin{array}{l}{R}_{\mathrm{e.g}}=R_{\mathrm{and}lt}-R_{s,\mathrm{e.g}}\\ =\left(R_t+R_s\right)-{\displaystyle \underset{0}{\overset{\mathrm{e.g}}{\int }}{A}_s\left(c\text{'}+\beta {\sigma }_{\mathrm{e.g}}^{\text{'}}\right)}\mathrm{i.e}\mathrm{e.g}\end{array}$$

where R _t is the foot resistance at which the soil behaves elastically, R _s is the total resistance of the wave.

wobei P₀ die äußere Last ist, einschließlich der Lasten aus dem Aufbau.Distributed load along the length of the pile: The surface load includes the external load acting on the pile head and the downward tension load. It can be estimated by: $$P_{\mathrm{e.g}}={\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="DE202022101355U1\_0023.png"\; state="\{\{state\}\}">P</figure-callout>}}_0+{\displaystyle \underset{0}{\overset{\mathrm{e.g}}{\int }}{A}_s\left(c\text{'}+\beta {\sigma }_{\mathrm{e.g}}^{\text{'}}\right)\mathrm{i.e}\mathrm{e.g}}$$

where P ₀ is the external load, including loads from the superstructure.

Equal Force Plane: It has been found that the area load acting on the pile increases from head to foot due to the influence of downward drag. And the bearing capacity of the pile decreases from head to foot, which is due to the influence of positive friction.

The condition of force equality is met when the load curve (formula 5) meets the load-bearing capacity curve (formula 6). In 2a the plane that runs through the intersection of the _Pz curve and the Rz curve is called the "force equilibrium plane - FEP".

• bei einem bestimmten Wert des Zehenwiderstands ändert sich die FEP-Position nicht allzu sehr, selbst wenn unterschiedliche Berechnungsmethoden oder unterschiedliche Reibungsparameter verwendet werden, da die Kurven der negativen und positiven Reibung symmetrisch sind;
• mit zunehmender Pfahllänge steigt der Wert des Fußwiderstandes geringfügig, während der Schaftwiderstand stark ansteigt; der FEP bewegt sich also tiefer in Richtung Fuß und umgekehrt. Durch die Auswahl der Pfahllänge kann man die Lage des FEP anpassen.

It can be stated that:

• for a given value of toe resistance, the FEP position does not change too much even when using different calculation methods or different friction parameters, since the negative and positive friction curves are symmetrical;
• with increasing pole length, the value of foot resistance increases slightly, while shaft resistance increases sharply; the FEP thus moves deeper towards the foot and vice versa. The position of the FEP can be adjusted by selecting the length of the pile.

In order to determine the correct FEP position, it is very important to determine the pile toe resistance as accurately as possible. FEP is not real, every stake always has a FEP.

Equality of settlement: At a point where subsoil settlement is equal to pile displacement and no slip occurs between the pile and the surrounding soil, friction is zero. Above this point, the soil settlement is greater than the pile displacement, so negative friction occurs. Below this point, the pile displacement is greater than the soil settlement, so that positive friction occurs. The plane that runs through this point is called the "Constraint Equality Plane - SEP".

Settlement of the subsoil: The settlements in the subsoil are caused by the consolidation of the soil. When estimating subsidence, not only the effects of direct and/or indirect loads acting on the subsoil must be considered, but also the effects of groundwater lowering, soil replenishment and/or settlement loads.

The subsoil in urban areas is under constant pressure from construction and other human activities. HCM city is among the top 5 largest cities in the world declining annually. Over the past 25 years, HCM city has subsided almost half a meter, and the main reason for this is the over-exploitation of groundwater for daily life. Many researchers have found that the soil in the suburban districts of HCMC is declining by 5 to 10 mm, which is mainly due to the excessive use of groundwater. In the meantime, many studies have found that the negative friction can reach a depth of tens of meters with a soil settlement of just a few millimeters. Negative friction is therefore a fact of construction practice in Ho Chi Minh City.

wobei k = A-Faktor abhängig von z/b und I/b, z = Tiefe von der Ladefläche, b = Breite des Floßes, / = Länge des Floßes.Estimates subsoil settlements based on calculations of overload stresses and pressure from external loads. The stress distribution in the subsoil under shallow foundations and surcharges can be calculated based on the Bousinesq solution: $${\sigma }_{\mathrm{e.g}}=kp$$

where k = A-factor dependent on z/b and I/b, z = depth from deck, b = width of raft, / = length of raft.

wobei ΔH_{i =} Dicke der Bodenschicht im Drainagebereich, γ_i = Eigengewicht, y^b _i = Auftriebsgewicht,γ_fill = Eigengewicht der oberen Bodenschicht (Auffüllung), h_fill = Dicke der oberen Bodenschicht (Auffüllung), γ_w = Wassergewicht, H = Tiefe vom Grundwasserspiegel bis zur Oberkante des druckbeaufschlagten Grundwasserleiters Untergrund unter Flachgründung und Auflast setzt sich aufgrund des Drucks, der durch die äußere Belastung entsteht, und kann auf verschiedene Weise bestimmt werden.Die Setzungsüberlagerung von Teilschichten wird zur Bestimmung der Bodensetzung verwendet, wobei die Steifigkeit der Platte außer Acht gelassen wird. Sie kann geschätzt werden durch: $$S={\displaystyle \sum _{i=1}^n{S}_i={\displaystyle \sum _{i=1}^n\frac{e_{1i}-e_{2i}}{1+e_{2i}}}}{h}_i$$

wobei S= die endgültige Setzung des Bodens am Boden, S_i = die endgültige Setzung der Bodenschicht i, n = die Anzahl der Bodenschichten, e_{1i =} der Hohlraumanteil der Bodenschicht i bei dem Lastniveau, das der Überlastspannung entspricht, ^e2i = der Hohlraumanteil der Bodenschicht i bei dem Lastniveau, das dem Gesamtwert der Überlastspannung und der Auflastspannung entspricht, h_i = die Dicke der Schicht i.Additional stress from the falling water level: $$\Delta {\sigma }_{\mathrm{e.g}}={\displaystyle \sum \Delta H_i\left(g_i-g_i^b\right)+g_{fill}{H}_{fill}+g_{w}H}$$

where ΔH _{i =} thickness of the soil layer in the drainage area, γ _i = dead weight, y ^b _i = buoyancy weight, γ _fill = dead weight of the upper soil layer (filling), h _fill = thickness of top soil layer (fill), γ _w = water weight, H = depth from water table to top of pressurized aquifer Subsoil under shallow foundation and ballast settles due to the pressure created by external loading and can occur in a number of ways The settlement superposition of sub-layers is used to determine soil settlement, ignoring the stiffness of the slab. It can be estimated by: $$S={\displaystyle \sum _{i=1}^n{S}_i={\displaystyle \sum _{i=1}^n\frac{e_{1i}-e_{2\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="DE202022101355U1\_0023.png,DE202022101355U1\_0025.png"\; state="\{\{state\}\}">i</figure-callout>}}}{1+e_{2i}}}}{H}_i$$

where S= the final settlement of soil at ground level, S _i = the final settlement of soil layer i, n = the number of soil layers, e _{1i =} the void fraction of soil layer i at the load level corresponding to the overload stress, ^e 2i = the void fraction of soil layer i at the load level corresponding to the total of the overload stress and the tipping stress, h _i = the thickness of layer i.

wobei w_i = Setzung des Knotens i, a_i,j = Bodenflexibilitätskoeffizient, der die Setzung am Knoten i infolge einer am Knoten j wirkenden Einheitslast angibt, P_j = am Knoten j wirkende Kraft.Subsoil settlements under the pile foundation can be estimated based on the Mindlin solution, where the slab and piles are divided into elements. The settlement of the subsoil at any node can be described as follows: $$w_i={\displaystyle \sum _{j=1}^n{a}_{ij}{P}_j}$$

where w _i = settlement of node i, a _i,j = soil flexibility coefficient giving settlement at node i due to a unit load acting at node j, P _j = force acting at node j.

The subsoil settlements at any point of the semi-elastic space under the foundation are a superposition of the settlements caused by any type of external loading and the interactions between the foundation structures.

In practice, the settlement of the ground under the pile driver cannot be accurately estimated either because of the settlement method and/or because of the determination of the external loads acting on the subsoil. As with the calculation of the friction between soil and pile, the settlement of the soil can therefore be estimated as the maximum possible value.

Pile displacement: Pile head displacement S _h is composed of the pile tip displacement sb and the elastic deformation of the pile s _e : $$s_H=s_b+s_e$$

Poulos & Davis (1980) schlugen vor: $$s_h=\frac{d_b}{30F}$$

The permissible pile head displacement is set at 2.5 to 10% of the pile diameter by British, French and Japanese standards, as well as by many other researchers. The Chinese standard sets the displacement at 40-80 mm, or: $$s_e=2PL/3EA+20$$

Poulos & Davis (1980) suggested: $$s_H=\frac{{\mathrm{i.e}}_b}{30f}$$

The elastic deformation of the pile can be determined as follows: $$s_e={\displaystyle \sum _0^D\frac{{\sigma }_i{D}_i}{E}}$$

Settlement Equality Level

The "Settlement Equality Level - SEP" is an important condition to determine whether a pile is subject to positive or negative friction.

• wenn die Pfahlverschiebung gleich der Bodensetzung ist, ist die Reibung an der Pfahl-Boden-Grenzfläche gleich Null;
• ist die Verschiebung des Pfahls größer als die Setzung des Bodens, entsteht negative Reibung;
• ist die Pfahlverschiebung kleiner als die Bodensetzung, tritt negative Reibung auf;
• der Schnittpunkt, an dem die Pfahlverschiebungskurve die Setzungskurve des Bodens schneidet, wodurch der Pfahl in zwei Hälften geteilt wird, in der oberen Hälfte, wo sich die negative Reibung entwickelt, und in der unteren Hälfte, wo sich die positive Reibung entwickelt. SEP ist eine reale Größe, die durch die Setzung des Untergrunds und die Pfahlverschiebung bestimmt wird.

This has been established:

• if the pile displacement is equal to the soil settlement, the friction at the pile-soil interface is zero;
• if the displacement of the pile is greater than the settlement of the ground, negative friction occurs;
• if the pile displacement is smaller than the ground settlement, negative friction occurs;
• the intersection where the pile-displacement curve intersects the soil settlement curve, dividing the pile into two halves, the upper half where negative friction develops and the lower half where positive friction develops. SEP is a real quantity that is determined by subsoil settlement and pile displacement.

• Pfähle gelten als tragfähig, wenn die FEP unterhalb der SEP liegt, da ihre Tragfähigkeit größer ist als die Last.
• Pfähle sind nicht in der Lage, die Last zu tragen, wenn FEP über SEP liegt, d. h. die Tragfähigkeit ist geringer als die äußere Last.

Pile construction: When designing piles where SEP and FEP are coordinated, three cases are possible:

• Piles are considered load-bearing if the SEP is below the SEP, since their bearing capacity is greater than the load.
• Piles are not able to bear the load when FEP is over SEP, i.e. bearing capacity is less than external load.

When these two planes coincide, the bearing capacity of the pile is equal to the external load, in which case these planes are referred to by many researchers as the neutral plane. Negative and positive friction can be determined when the neutral plane is in this equilibrium.

• Kumulative negative Reibung: $P_{fr,x}={{\displaystyle {\sum }_1^nƒ}}_i\times U\times {\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="DE202022101355U1\_0023.png"\; state="\{\{state\}\}">h</figure-callout>}}_0$
  
• Positive Reibung: R_ƒr,x = P_ƒr,h-x
• Lastverteilung:P_x = P + P_fr,x
• Widerstandsverteilung: R_x = R_toe + R_ƒr,x
• Abrechnung des Stapels: S_p,x = S_ermöglichen - S_e
• Zulässige Setzung des ${\text{Pfahls:S}}_{erm\ddot{o}glichen}=\frac{2PL}{3EA}+20\mathrm{<figure-callout\; id="40"\; label="o\; r"\; filenames="DE202022101355U1\_0023.png,DE202022101355U1\_0024.png"\; state="\{\{state\}\}">o</figure-callout>}r40-80mm$
  
• Elastische Verformung des $\text{Pfahls:}{S}_e={\displaystyle {\sum }_1^{\text{n}}\frac{{\sigma }_i\times h_0}{E}}$
  
• Besiedlung des Bodens: ${\displaystyle {\sum }_1^{\text{n}}\frac{e_{1i}-e_{2\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="DE202022101355U1\_0023.png,DE202022101355U1\_0025.png"\; state="\{\{state\}\}">i</figure-callout>}}}{1+e_{2i}}}{h}_i$
  
  $$\Delta H=H_{FEP}-H_{SEP}\ge 0$$
  

3 12 shows the plan of the Bitexco tower rammed in accordance with an embodiment of the present disclosure. Bitexco Tower was built in District 1, HCM City and is 68 stories tall. Some soil geotechnical parameters in District 1, HCM City are shown in Table 1. The soil layer directly under the foundation is a 31 m thick layer of fine sand of medium density. The fine sand is covered by a 15 m thick layer of hard yellow-brownish clay. Below the clay there is a layer of dense, medium-sized sand down to a depth of 100 m. The tower has a 4 m thick large-scale raft supported by 109 1.5 m diameter piles, of which 69 75 m piles at the edge of the raft and 40 85 m piles in the middle of the raft. The raft and the piles were modeled and analyzed using the PRAB program.

• Cumulative negative friction: $P_{f\mathrm{right},x}={{\displaystyle {\sum }_1^nƒ}}_i\times u\times {\mathrm{<figure-callout\; id="0"\; label="H"\; filenames="DE202022101355U1\_0023.png"\; state="\{\{state\}\}">H</figure-callout>}}_0$
  
• Positive friction: R _ƒr,x = P _ƒr,hx
• Load sharing:P _x = P + P _fr,x
• Resistance distribution: R _x = R _toe + R _ƒr,x
• Stack accounting: S _p,x = S _allow - S _e
• Permissible setting of ${\text{Pfahls: S}}_{e\mathrm{right}m\ddot{O}GlicHen}=\frac{2PL}{3EA}+20O\mathrm{right}40-80mm$
  
• Elastic deformation of $\text{stakes:}{S}_e={\displaystyle {\sum }_1^{\text{n}}\frac{{\sigma }_i\times H_0}{E}}$
  
• Colonization of the soil: ${\displaystyle {\sum }_1^{\text{n}}\frac{e_{1i}-e_{2\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="DE202022101355U1\_0023.png,DE202022101355U1\_0025.png"\; state="\{\{state\}\}">i</figure-callout>}}}{1+e_{2i}}}{H}_i$
  
  $$\Delta H=H_{fEP}-H_{SEP}\ge 0$$
  

• •Lastfall 1, bei dem die äußere Last nur ein Teil der Last ist, die vom Floß getragen wird - SEP 1.
• •Lastfall 2, bei dem die äußere Last aus einem Teil der vom Floß zu tragenden Gebäudelast plus der städtischen Last (in dieser Studie nehmen wir 10 KN an) besteht - SEP 2, oder;
• • Lastfall 3, in dem die äußere Last die gesamte Last des Gebäudes ist, sie wird als gleichmäßige Last betrachtet und wirkt auf die starre Platte auf halbelastischem Raum, verteilt im Untergrund durch Boussinesq-Lösung - SEP 3.

4 12 shows the estimated results of pile load distribution, pile displacement, and ground settlement according to an embodiment of the present disclosure. The analysis results with PRAB show that the load distribution is different along 109 piles. The center piles have a neutral plane near the pile head and the outer piles have a neutral plane midway along the pile length. The load distribution of the pole at the raft corner.

• •Load case 1 where the external load is only part of the load carried by the raft - SEP 1.
• • Load case 2, where the external load consists of part of the building load to be supported by the raft plus the urban load (in this study we assume 10 KN) - SEP 2, or;
• • Load case 3, in which the external load is the total load of the building, it is considered as a uniform load and acts on the rigid plate on semi-elastic space, distributed in the subsoil by Boussinesq solution - SEP 3.

This means that the position of the SEP determined by the PRAB agrees well with the results of the manual calculation when the subsoil settlement is calculated according to formula (10).

5 12 shows the comparison of the neutral plane (SEP and FEP) calculated by PRAB with the location of the FEP determined by various methods according to an embodiment of the present disclosure. 5 shows a comparison of the position of the neutral plane (when SEP coincides with FEP) determined by PRAB with the position of the FEP determined by different analytical methods. With the methods used, the base resistance of the pole assumes a minimum value that can be compared with the results of the load test. The load at the pile head can be calculated using any method based on the stiffness of the raft. It can be seen that: All FEPs are below the neutral plane, which means that the pile has greater bearing capacity than required. If the subsoil behavior is carefully considered, the pile length of 85 m can be significantly reduced. In this case, adjust the length of the stake by reducing it until the FEP matches the SEP.

• Das Verhalten der Last und die Tragfähigkeit eines Pfahls werden durch FEP charakterisiert. Der Fußwiderstand des Pfahls sollte konservativ gewählt werden, da die Verschiebung des Pfahls nur von der auf den Pfahlfuß wirkenden Last abhängt. Die am Pfahlkopf wirkende äußere Last ist gegeben, so dass der Schaftwiderstand der einzige Faktor ist, der die Lage des FEP beeinflusst. Da die negativen und positiven Reibungskurven symmetrisch sind, ändert sich die Lage der Kraftgleichheitsebene nicht wesentlich. Die Lage der FEP wird auf diese Weise bestimmt, um konservativer zu sein und sicherzustellen, dass die Tragfähigkeit größer ist als die Gesamtlast (einschließlich externer Last und Abwärtskraft). Die FEP liegt normalerweise in der unteren Hälfte des Pfahls.

The presented system can explain the behavior of piles well. The dimensioning of the pile taking into account the subsequent tension is relevant on the equal settlement level (SEP) and the equal force level (FEP):

• The behavior of the load and the bearing capacity of a pile are characterized by FEP. The base resistance of the pile should be chosen conservatively since the displacement of the pile depends only on the load acting on the pile base. The external load acting at the pile head is given, so shaft resistance is the only factor influencing the location of the FEP. Since the negative and positive friction curves are symmetrical, the position of the force balance plane does not change significantly. The location of the FEP is determined in this way to be more conservative and ensure that the bearing capacity is greater is than the total load (including external load and downward force). The FEP is usually in the lower half of the stake.

The behavior of soil settlement and pile displacement is characterized by SEP. Soil settlement is estimated as the total settlement caused by the pressure due to external loads from foundations, piles or surcharge or by the subsidence of groundwater. SEP goes through the point where the settlement of the soil is equal to the displacement of the pile. This point divides the pile into two halves, with soil settlement greater than soil settlement in the upper half and pile displacement greater than soil settlement in the lower half. By adjusting the length of the pile, one can determine the desired displacement.

Planning piles with negative friction in mind consists of matching FEP and SEP. For this purpose, the length of the pile can be increased or decreased. The pile is considered to be capable of bearing the design load if FEP is less than SEP. The amount of negative and positive friction can be determined when FEP and SEP match

The figures and the preceding description give examples of embodiments. Those skilled in the art will understand that one or more of the elements described may well be combined into a single functional element. Alternatively, certain elements can be broken down into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of the processes described herein may be rearranged and is not limited to the manner described herein. Also, the acts of a flowchart need not be performed in the order shown; also, not all actions have to be performed. Also, the actions that are not dependent on other actions can be performed in parallel with the other actions. The scope of the embodiments is in no way limited by these specific examples. Numerous variations are possible, regardless of whether they are explicitly mentioned in the description or not, e.g. B. Differences in structure, dimensions and use of materials. The scope of the embodiments is at least as broad as indicated in the following claims.

Advantages, other benefits, and solutions to problems have been described above with respect to particular embodiments. However, the benefits, advantages, problem solutions, and components that can cause an advantage, benefit, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all claims.

Reference List

100

A system for planning piles considering downside resistance

102

A data acquisition unit

104

An analysis unit

106

An optimization unit

402

NP by PRAB

404

load case 1

406

load case 2

408

load case 3

410

stack

502

FEP to TCVN

504

FEP from Beta-M

506

FEP by Meyerhof

Claims (8)

A system for designing piles considering downward resistance, the system comprising: a data acquisition unit configured to receive load data from piles and soil data; an analysis unit connected to the data acquisition unit to create either a soil or a pole model; and an optimization unit connected to the analysis unit to perform a static incremental analysis of the pile and the soil model, thereby evaluating the bearing capacity and the deformation of the pile using a limit curve. system after claim 1 , where the load data are external loads acting on piles and soil, derived from the superstructure calculation, where the pile data are pile diameter and pile length, where the pile data and soil data are used to calculate the pile bearing capacity. system after claim 1 , where the pile model is an elastic relationship and a soil-pile model is elastoplastic. system after claim 1 , where the piles are designed taking into account the negative friction in such a way that the force equality plane (FEP) coincides with the settlement equality plane (SEP). system after claim 4 , in which the piles are installed in a consolidating soil such that the load distribution along a pile under the condition of force equality must be less than or equal to its bearing capacity. system after claim 4 , where the distributed load acting on the pile from head to toe increases due to the influence of a possible downward draft and the distributed bearing capacity of the pile from head to toe decreases due to the influence of positive friction. system after claim 4 , where if the pile displacement is equal to the possible ground settlement, the negative friction at the pile-soil interface is zero, while if the pile displacement is greater than the ground settlement, there is no negative friction, where if the pile displacement is less than the ground settlement is negative friction occurs. system after claim 4 , where piles are considered capable of bearing external loads if the FEP's layer is below the SEP's layer because its bearing capacity is greater than the external load, where piles are not capable of bearing the load, when the FEP is above the SEP, which means its carrying capacity is less than the external load.

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